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At least 73 records · Page 4Linked to original sources
PubMed2004

Three putative murine Teashirt orthologues specify trunk structures in Drosophila in the same way as the Drosophila teashirt gene.

Drosophila teashirt (tsh) functions as a region-specific homeotic gene that specifies trunk identity during embryogenesis. Based on sequence homology, three tsh-like (Tsh) genes have been identified in the mouse. Their expression patterns in specific regions of the trunk, limbs and gut raise the possibility that they may play similar roles to tsh in flies. By expressing the putative mouse Tsh genes in flies, we provide evidence that they behave in a very similar way to the fly tsh gene. First, ectopic expression of any of the three mouse Tsh genes, like that of tsh, induces head to trunk homeotic transformation. Second, mouse Tsh proteins can rescue both the homeotic and the segment polarity phenotypes of a tsh null mutant. Third, following ectopic expression, the three mouse Tsh genes affect the expression of the same target genes as tsh in the Drosophila embryo. Fourth, mouse Tsh genes, like tsh, are able to induce ectopic eyes in adult flies. Finally, all Tsh proteins contain a motif that recruits the C-terminal binding protein and contributes to their repression function. As no other vertebrate or fly protein has been shown to induce such effects upon ectopic expression, these results are consistent with the idea that the three mouse Tsh genes are functionally equivalent to the Drosophila tsh gene when expressed in developing Drosophila embryos.

Animals↗
PubMed2005

The twisted gene encodes Drosophila protein O-mannosyltransferase 2 and genetically interacts with the rotated abdomen gene encoding Drosophila protein O-mannosyltransferase 1.

The family of mammalian O-mannosyltransferases includes two enzymes, POMT1 and POMT2, which are thought to be essential for muscle and neural development. Similar to mammalian organisms, Drosophila has two O-mannosyltransferase genes, rotated abdomen (rt) and DmPOMT2, encoding proteins with high homology to their mammalian counterparts. The previously reported mutant phenotype of the rt gene includes a clockwise rotation of the abdomen and defects in embryonic muscle development. No mutants have been described so far for the DmPOMT2 locus. In this study, we determined that the mutation in the twisted (tw) locus, tw(1), corresponds to a DmPOMT2 mutant. The twisted alleles represent a complementation group of recessive mutations that, similar to the rt mutants, exhibit a clockwise abdomen rotation phenotype. Several tw alleles were isolated in the past; however, none of them was molecularly characterized. We used an expression rescue approach to confirm that tw locus represents DmPOMT2 gene. We found that the tw1 allele represents an amino acid substitution within the conserved PMT domain of DmPOMT2 (TW) protein. Immunostaining experiments revealed that the protein products of both rt and tw genes colocalize within Drosophila cells where they reside in the ER subcellular compartment. In situ hybridization analysis showed that both genes have essentially overlapping patterns of expression throughout most of embryogenesis (stages 8-17), while only the rt transcript is present at early embryonic stages (5 and 6), suggesting its maternal origin. Finally, we analyzed the genetic interactions between rt and tw using several mutant alleles, RNAi, and ectopic expression approaches. Our data suggest that the two Drosophila O-mannosyltransferase genes, rt and tw, have nonredundant functions within the same developmental cascade and that their activities are required simultaneously for possibly the same biochemical process. Our results establish the possibility of using Drosophila as a model system for studying molecular and genetic mechanisms of protein O-mannosylation during development.

Amino Acid Sequence↗
PubMed1995

A single ancestral gene of the human LIM domain oncogene family LMO in Drosophila: characterization of the Drosophila Dlmo gene.

Members of the human TTG/RBTN family, now renamed 'LMO' for LIM-only proteins, encode proteins with two tandem copies of a LIM motif. There are three members of this family, two have been isolated at the sites of chromosomal translocations in T-cell leukaemia. The function of the LIM motifs is at present unknown. We found that the LMO-2 gene is highly conserved between mammals, Drosophila and yeast. As a first step to obtain a model system for studying the function of the LIM motifs we have isolated the Drosophila homologue Dlmo. In contrast to mammals Drosophila appears to have only one lmo gene. A 2087 bp cDNA clone was isolated from a larval cDNA library, encoding a protein of 266 amino acids. A second transcript with an alternative 5' end was identified in RNA from embryos. The Drosophila lmo protein consists of two tandem copies of the conserved LIM domain characteristic of the human LMO family and an extended amino and carboxy terminus, which is not present in the human proteins. The amino acid sequence similarity with human LMO-1 and LMO-2 in LIM 1 is 79% and 69% and in LIM-2 90% and 60%, respectively. In addition a short stretch of 25 nucleotides with a homology of 83% between LMO-2 and Dlmo is found in the 3' UTR. Dlmo, like LMO-1, has an intron after the second LIM encoding region, which is not present in LMO-2. It is expressed maternally and at a high level in early embryogenesis as well as in adults. Interestingly we observed that the Dlmo protein is immunologically related to LMO-2 and can be detected by immunohistochemistry in early cellular blastoderm embryos. The gene was localised to a genetically well characterized region (17C on the X chromosome) opening the way for identification of mutations.

Adaptor Proteins, Signal Transducing↗
PubMed1991

Evaluation of Drosophila for screening developmental toxicants: test results with eighteen chemicals and presentation of a new Drosophila bioassay.

The objective of this study was to generate a comprehensive data set of chemically induced malformations in Drosophila using a detailed morphological examination of the entire fly (phase one). These data were analyzed, in blind, with the goal of developing a standardized set of criteria which could be used in a new, rapid, and economical Drosophila bioassay useful in the preliminary screening for potential developmental toxicants. After 32 chemicals were tested, formalized criteria were developed to form the basis of a new Drosophila bioassay. These criteria were then applied to the data from the same 32 chemicals (phase two). The data from only 18 of these chemicals met all requirements for evaluation, e.g., statistical significance, minimum fly numbers, sufficient challenge concentration administered, etc. In the new bioassay, rather than the detailed and time-consuming examination of the entire fly for a multitude of morphological defects, only two specific anatomical sites are examined. These sites are the humeral bristle and the wing blade, with focus placed on two structural defects--a bent bristle and a notch in the wing. These defects were the only two external malformations among the multitude of defects observed in flies treated in the first phase with the 32 chemicals which demonstrated the following characteristics: 1) A consistent concentration-response in flies treated with a variety of developmental toxicants; 2) a lack of response with most presumptive non-developmental toxicants; and 3) consistently low-background incidences in control flies. In both phases, developing Drosophila were exposed to the test agents from the egg through three larval stages by incorporating a range of concentrations of each chemical into the culture medium. Emerging adults were examined for an array of defects as part of a detailed morphological examination in the first phase, including bent bristles and wing notches. In the second phase, only bent bristle and wing notch data were evaluated. The incidences of bent humeral bristles and wing notches from flies exposed to each of the 18 chemicals were compared with those of concurrent controls. Of the 18 chemicals that could be evaluated using the new bioassay, 13 were known developmental toxicants while the remaining 5 were presumptive negative agents. Ten of the 13 mammalian developmental toxicants were correctly identified with this test (false negative rate of 23%). Four of five apparent non-developmental toxicants were correctly identified for a false positive rate of 20%.(ABSTRACT TRUNCATED AT 400 WORDS)

Abnormalities, Drug-Induced↗
PubMed1976

Genetics of esterases in Drosophila. IV. Slow-migrating S-esterase in Drosophila of the virilis group.

A slow-migrating beta-esterase (S-esterase) is described which has been detected in Drosophila montana, Drosophila imeretensis, and some stocks of Drosophila virilis when mixtures of alpha- and beta-naphthyl acetate are used as substrates in histochemical reactions after electrophoresis. Sexual dimorphism for S-esterase has been demonstrated. This esterase is contained in male genitalia only, predominantly in the ejaculatory bulb (waxy plug). It appears 3-4 days after emergence of flies. In hybrids between S+ and So species, the activity of the slow esterase is either decreased or inhibited. An autonomous synthesis of the S- esterase in the ejaculatory bulb was established by transplantation of imaginal genital discs into larvae of different Drosophila stocks. Based on analysis of physiochemical and immunochemical properties, S-esterase is suggested to be an independent fraction of esterase, possibly dimeric, which does not cross-react with beta-esterase antiserum.

Animals↗
PubMed1984

Integration of Drosophila heat-shock genes transfected into cultured Drosophila melanogaster cells.

We have used DNA-mediated gene transfer to introduce into Drosophila melanogaster cells DNA sequences for which no selective criteria exist. We have introduced a Drosophila heat-shock locus into cultured Drosophila cells by calcium phosphate cotransfection with the copia vector pCV31gpt and selection for xanthine utilization. We recovered cell lines containing between three and about 50 copies of both pCV31gpt and pMH10A, a cloned 87 A7 hsp70 heat-shock locus that encodes a mutant 40,000-dalton heat-shock protein (hsp40). The stable inheritance of the transformed DNAs argues that the input DNAs have integrated into the genome. We show that this is indeed the case for one cell line by cloning back the transfected DNA and detecting the flanking chromocentral sequences by in situ hybridization. Surprisingly, the integrated hsp70 genes are not expressed. This report represents the first example of the cointroduction of DNA sequences into Drosophila cells by cotransfection with a dominant selectable marker.

Animals↗
PubMed1992

A simple vacuum dot-blot hybridisation assay for the detection of Drosophila A and C viruses in single Drosophila.

Specific cDNA clones were constructed from the single stranded RNA genome of Australian isolates of both Drosophila A and C viruses. These clones were used to develop a nucleic acid hybridisation assay capable of detecting reliably 3.9 ng of DAV and 19.3 ng of DCV virus particles, respectively. The sensitivity of the assays were largely unaffected by soluble host material. Single Drosophila naturally infected or artificially inoculated with DAV or DCV were found to contain in excess of 130 ng of virus. The results presented here demonstrate that the vacuum dot-blotting protocol and the hybridisation assays developed are capable of detecting DAV and DCV in single Drosophila and may therefore be applied to the study of DAV and DCV in natural Drosophila communities.

Animals↗
PubMed2001

Drosophila regulatory factor X is an embryonic type I sensory neuron marker also expressed in spermatids and in the brain of Drosophila.

We report the expression pattern of a Drosophila transcription factor, Drosophila regulatory factor X (dRFX), which belongs to the RFX winged-helix transcription factor family. dRFX is distributed in type I sensory neuron lineage of the peripheral nervous system throughout Drosophila development and thus represents the first described type I lineage characteristic marker in Drosophila. In addition, dRFX is also detected in the brain throughout development and in spermatids in adult flies.

Animals↗
PubMed2005

The novel Drosophila lysosomal enzyme receptor protein mediates lysosomal sorting in mammalian cells and binds mammalian and Drosophila GGA adaptors.

Biogenesis of lysosomes depends in mammalian cells on the specific recognition and targeting of mannose 6-phosphate-containing lysosomal enzymes by two mannose 6-phosphate receptors (MPR46, MPR300), key components of the extensively studied receptor-mediated lysosomal sorting system in complex metazoans. In contrast, the biogenesis of lysosomes is poorly investigated in the less complex metazoan Drosophila melanogaster. We identified the novel type I transmembrane protein lysosomal enzyme receptor protein (LERP) with partial homology to the mammalian MPR300 encoded by Drosophila gene CG31072. LERP contains 5 lumenal repeats that share homology to the 15 lumenal repeats found in all identified MPR300. Four of the repeats display the P-lectin type pattern of conserved cysteine residues. However, the arginine residues identified to be essential for mannose 6-phosphate binding are not conserved. The recombinant LERP protein was expressed in mammalian cells and displayed an intracellular localization pattern similar to the mammalian MPR300. The LERP cytoplasmic domain shows highly conserved interactions with Drosophila and mammalian GGA adaptors known to mediate Golgi-endosome traffic of MPRs and other transmembrane cargo. Moreover, LERP rescues missorting of soluble lysosomal enzymes in MPR-deficient cells, giving strong evidence for a function that is equivalent to the mammalian counterpart. However, unlike the mammalian MPRs, LERP did not bind to the multimeric mannose 6-phosphate ligand phosphomannan. Thus ligand recognition by LERP does not depend on mannose 6-phosphate but may depend on a common feature present in mammalian lysosomal enzymes. Our data establish a potential important role for LERP in biogenesis of Drosophila lysosomes and suggest a GGA function also in the receptor-mediated lysosomal transport system in the fruit fly.

ADP-Ribosylation Factors↗
PubMedDate not supplied

Isolation and characterization of the Drosophila ornithine decarboxylase locus: evidence for the presence of two transcribed ODC genes in the Drosophila genome.

The polymerase chain reaction (PCR) was used to isolate two Drosophila ornithine decarboxylase (ODC) genes. Two mixtures of degenerate oligonucleotides corresponding to peptides that are fully conserved among ODCs from widely diverged species were used as opposing primers in the PCR with cDNA or genomic DNA as templates. Sequence analysis of the resulting DNA products confirmed their identity as ODC fragments. The genomic PCR product was then used as a probe for screening a Drosophila genomic library, resulting in the isolation of genomic clones representing two distinct ODC genes (dODC1 and dODC2). Sequence analysis of both genes demonstrated that although varying at their coding and noncoding regions, their overall structure is extremely similar containing 6 exons and 5 short introns. Southern blot and sequence analyses revealed that the two ODC genes are arranged in a tandem head-to-tail configuration. Both ODC genes were assigned by in situ hybridization analysis to position 44A on the right arm of the second chromosome. The isolation of cDNA clones corresponding to these two ODC genes demonstrated that both are transcribed in the adult fly. We hope that the isolation of genomic and cDNA clones of Drosophila ODC will permit the investigation of the expression of ODC during Drosophila development and the role of polyamines in this process.

Amino Acid Sequence↗
PubMedDate not supplied

Mitochondrial DNA variation among the Drosophila athabasca semispecies and Drosophila affinis.

Morphology, allozymes, and levels of postreproductive isolation indicate that the semispecies of Drosophila athabasca are as recently diverged as typical populations within a Drosophila species. However, levels of behavioral isolation, divergence in male mating song, and divergence in X-chromosome inversions suggest a much more ancient divergence. In this article, we have examined mitochondrial DNA restriction site variation within and among the three semispecies. These data support the hypothesis that the three semispecies of Drosophila athabasca are at least as recently diverged as are typical populations within other species of Drosophila. Male mating song, behavioral isolation, and X-chromosome differences thus appear to have evolved very rapidly. In addition, hypothesized phylogenetic relationships of these three semispecies, based on our mtDNA data, are identical to those based on allozymes and chromosomal inversions. According to this phylogeny, recency of ancestry is not well correlated with levels of behavioral isolation, whereas patterns of sympatry and allopatry are. These patterns strongly implicate the action of selection in the rapid evolution of behavioral isolation and X-chromosome gene arrangement.

Animals↗
PubMed1999

Nonfixed duplication containing the Adh gene and a truncated form of the Adhr gene in the Drosophila funebris species group: different modes of evolution of Adh relative to Adhr in Drosophila.

The sequence of the genomic region that contains the Adh and Adhr genes of Drosophila funebris was used to demonstrate that both genes are present in species of the funebris group. The sequence of this genomic region reveals a 2.9-kb tandem duplication which encompasses 1.6 kb of the 5' flanking region, the entire Adh gene, and two thirds of the first exon of the Adhr gene in D. funebris. This duplication is not fixed in this species since some strains do not carry the duplication. The Adh duplication has also been found in another species of the funebris group, Drosophila macrospina macrospina. The sequence analysis of the 5'-flanking region of the Adh gene indicates a single promoter and shows stretches of high similarity with cis-acting elements responsible for the expression of Adh in Drosophila melanogaster. In confirmation of this indication, the larval and adult transcripts have the same length, which corresponds to the transcription from the promoter proximal to the coding region. The codon bias of the Adh gene of D. funebris is among the lowest reported for any Adh gene in the Drosophilidae species and is very similar to that of the Adhr gene. The Adhr gene evolves slightly faster than Adh at synonymous positions. At nonsynonymous positions, the Adh gene evolves 2.5 times faster than Adhr in the species pair D. funebris-Drosophila immigrans, while in other interspecific comparisons the average is about 1.25. However, in comparisons between some species within the melanogaster and obscura groups, Adh evolves at half the rate of Adhr. The phylogenetic trees constructed with the coding region of the Adh gene cluster D. funebris and D. immigrans and clearly separate them from the clade in which virilis, repleta, and Hawaiian species are grouped. Using the evolutionary synonymous rate estimated for Hawaiian species, the divergence time of D. funebris from the virilis-repleta-Hawaiian clade was estimated as 34.3 Myr, and the divergence time of D. funebris and D. immigrans was estimated as 23.5 Myr.

Alcohol Dehydrogenase↗
PubMed2002

Sexual isolation between two sibling species with overlapping ranges: Drosophila santomea and Drosophila yakuba.

Drosophila yakuba is widespread in Africa, whereas D. santomea, its newly discovered sister species, is endemic to the volcanic island of São Tomé in the Gulf of Guinea. Drosophila santomea probably formed after colonization of the island by a D. yakuba-like ancestor. The species presently have overlapping ranges on the mountain Pico do São Tomé, with some hybridization occurring in this region. Sexual isolation between the species is uniformly high regardless of the source of the populations, and, as in many pairs of Drosophila species, is asymmetrical, so that hybridizations occur much more readily in one direction than the other. Despite the fact that these species meet many of the conditions required for the evolution of reinforcement (the elevation of sexual isolation by natural selection to avoid maladaptive interspecific hybridization), there is no evidence that sexual isolation between the species is highest in the zone of overlap. Sexual isolation is due to evolutionary changes in both female preference for heterospecific males and in the vigor with which males court heterospecific females. Heterospecific matings are also slower to take place than are homospecific matings, constituting another possible form of reproductive isolation. Genetic studies show that, when tested with females of either species, male hybrids having a D. santomea X chromosome mate much less frequently with females of either species than do males having a D. yakuba X chromosome, suggesting that the interaction between the D. santomea X chromosome and the D. yakuba genome causes behavioral sterility. Hybrid F1 females mate readily with males of either species, so that sexual isolation in this sex is completely recessive, a phenomenon seen in other Drosophila species. There has also been significant evolutionary change in the duration of copulation between these species; this difference involves genetic changes in both sexes, with at least two genes responsible in males and at least one in females.

Animals↗
PubMed1990

Purified Drosophila transcription factor, Adh distal factor-1 (Adf-1), binds to sites in several Drosophila promoters and activates transcription.

Adh distal factor-1 (Adf-1) is a sequence-specific DNA-binding activity originally identified in Drosophila tissue culture cells and embryos. Adf-1 binds to upstream recognition elements in each of the two promoters of the Drosophila alcohol dehydrogenase gene (Adh), and binding of Adf-1 to the Adh distal promoter site activates transcription. We have carried out a mutational analysis of the Adh distal promoter using both an in vitro transcription assay and a transient transfection assay in Drosophila tissue culture cells, and in both cases find that deletion of sequences required for Adf-1 binding leads to a 3-4-fold drop in transcription. We have purified Adf-1 and demonstrate by a sodium dodecyl sulfate-gel renaturation assay that it is a 34-kDa protein. Purified Adf-1 activates Adh distal promoter transcription in vitro in a binding site-dependent manner. DNase I footprint analysis shows that the purified protein binds not only to the two previously characterized sites in Adh but also to transcriptional regulatory elements in the dopa decarboxylase (Ddc) and Antennapedia (Antp) P1 promoters. Thus, it appears that Adf-1 may play an important role not only in the regulation of Adh expression but also in the transcription of other Drosophila genes as well.

Alcohol Dehydrogenase↗
PubMed2003

The PRAT purine synthesis gene duplication in Drosophila melanogaster and Drosophila virilis is associated with a retrotransposition event and diversification of expression patterns.

The Drosophila melanogaster Prat gene encodes amidophosphoribosyltransferase (PRAT; EC 2.4.2.14), which performs the first step in de novo purine nucleotide synthesis. Prat mutations have a recessive lethal phenotype that is found for other genes encoding enzymes in this pathway. The D. melanogaster genome project has revealed a second gene, CG10078 or Prat2, encoding a protein with 76% amino acid sequence identity with Prat. The two genes map to different arms of chromosome 3 and have different intron/exon organizations, as we confirmed by cDNA sequence analysis of Prat2. With the goal to determine the functional significance of this gene duplication, we isolated and sequenced two PRAT-encoding genes from Drosophila virilis. We find that the two D. virilis genes are orthologous to the two D. melanogaster genes in terms of intron/exon organization, amino acid coding sequence, and 5' noncoding sequence. The absence of introns in both DmelPrat and DvirPrat genes suggests that Prat originated from a retrotransposition of Prat2 and that the gene duplication has been preserved in the two species since their divergence approximately 40 million years ago. Analysis of mRNA expression in development shows that maternal expression, detected in adult ovaries and embryos prior to the onset of zygotic transcription, is present for Prat but not Prat2 in both species. Taken together, these findings support the notion that two PRAT-encoding genes have evolved distinct functions in both Drosophila species.

Amidophosphoribosyltransferase↗
PubMed2002

Conservation of gene order, structure and sequence between three closely linked genes in Drosophila melanogaster and Drosophila virilis.

In Drosophila melanogaster, the apparently unrelated genes anon-66Da, RpL14, and anon-66Db (from telomere to centromere) are located on a 5547 bp genomic fragment on chromosome arm 3L at cytological position 66D8. The three genes are tightly linked, and flanked by two relatively large genes with unknown function. We have taken a comparative genomic approach to investigate the evolutionary history of the three genes. To this end we isolated a Drosophila virilis 7.3 kb genomic fragment which is homologous to a 5.5 kb genomic region of D. melanogaster. Both fragments map to Muller's element D, namely to section 66D in D. melanogaster and to section 32E in D. virilis, and harbor the genes anon-66Da, RpL14, and anon-66Db. We demonstrate that the three genes exhibit a high conservation of gene topography in general and in detail. While most introns and intergenic regions reveal sequence divergences, there are, however, a number of interspersed conserved sequence motifs. In particular, two introns of the RpL14 gene contain a short, highly conserved 60 nt long sequence located at corresponding positions. This sequence represents a novel Drosophila small nucleolar RNA, which is homologous to human U49. Whereas DNA flanking the three genes shows no significant interspecies homologies, the 3'-flanking region in D. virilis contains sequences from the transposable element Penelope. The Penelope family of transposable elements has been shown to promote chromosomal rearrangements in the D. virilis species group. The presence of Penelope sequences in the D. virilis 7.3 kb genomic fragment may be indicative for a transposon-induced event of transposition which did not yet scramble the order of the three genes but led to the breakdown of sequence identity of the flanking DNA.

Amino Acid Sequence↗
PubMed2003

Transcription control of a gene for Drosophila transcription factor, DREF by DRE and cis-elements conserved between Drosophila melanogaster and virilis.

A DNA replication-related element (DRE)-binding factor (DREF) has been revealed to be an important transcription factor for activating promoters of cell proliferation and differentiation related genes. The amino acid sequences of DREF are conserved in evolutionary separate Drosophila species, Drosophila melanogaster (Dm) and Drosophila virilis (Dv) in three regions. In the present study, evidence was obtained that there are several highly conserved regions in the 5' flanking region between the DmDREF and DvDREF genes. Band mobility shift assays using oligonucleotides corresponding to these conserved regions revealed that specific trans-acting factors can bind to at least three regions -554 to -543 (5'-TTTGTTCTTGCG), -81 to -70 (5'-GCCCACGTGGCT) and +225 to +234 (5'-GCAATCAGTG). Using a transient luciferase expression assay, we demonstrated that the region -554 to -543 functions as a negative regulatory element for DmDREF promoter activity, while the regions -77 to -70 (5'-ACGTGGCT) and +225 to +236 (5'-GCAATCAGTGTT) function as positive regulatory elements. In previous studies, we observed that expression of the homeodomain protein Zerknüllt (Zen) represses PCNA gene transcription, by reducing the DNA binding activity of DREF. Here we show Zen downregulates DREF gene promoter activity through action on the region between +241 and +254 (5'-AGAATACTCAACA). In addition, the DmDREF promoter contains five DREs. Using a double stranded RNA-mediated interference method, we generated evidence that expression of DmDREF could be auto-regulated by DREF through the third DRE located at +211 to +218. In living flies we obtained results consistent with those obtained in vitro and in cultured cells. The study thus indicates that DmDREF is effectively regulated via highly conserved regions between the DmDREF and DvDREF promoters, suggesting the existence of common regulatory factors, and that DmDREF can be positively regulated by itself via the third DRE located in its most highly conserved region.

5' Flanking Region↗
PubMed1998

Autoregulation at the level of mRNA 3' end formation of the suppressor of forked gene of Drosophila melanogaster is conserved in Drosophila virilis.

The Drosophila melanogaster Suppressor of forked [Su(f)] protein shares homology with the yeast RNA14 protein and the 77-kDa subunit of human cleavage stimulation factor, which are proteins involved in mRNA 3' end formation. This suggests a role for Su(f) in mRNA 3' end formation in Drosophila. The su(f) gene produces three transcripts; two of them are polyadenylated at the end of the transcription unit, and one is a truncated transcript, polyadenylated in intron 4. Using temperature-sensitive su(f) mutants, we show that accumulation of the truncated transcript requires wild-type Su(f) protein. This suggests that the Su(f) protein autoregulates negatively its accumulation by stimulating 3' end formation of the truncated su(f) RNA. Cloning of su(f) from Drosophila virilis and analysis of its RNA profile suggest that su(f) autoregulation is conserved in this species. Sequence comparison between su(f) from both species allows us to point out three conserved regions in intron 4 downstream of the truncated RNA poly(A) site. These conserved regions include the GU-rich downstream sequence involved in poly(A) site definition. Using transgenes truncated within intron 4, we show that sequence up to the conserved GU-rich domain is sufficient for production of the truncated RNA and for regulation of this production by su(f). Our results indicate a role of su(f) in the regulation of poly(A) site utilization and an important role of the GU-rich sequence for this regulation to occur.

Amino Acid Sequence↗