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Transcriptional mapping and nucleotide sequence of the Listeria monocytogenes hlyA region reveal structural features that may be involved in regulation.

DNA sequence analysis of the regions adjacent to the hlyA gene, which encodes listeriolysin O, an essential virulence factor of Listeria monocytogenes, revealed the presence of two open reading frames (ORFs): ORF D located 304 base pairs downstream from hlyA, and ORF U located 224 base pairs upstream from and in opposite direction to hlyA. Promoter mapping performed with RNAs extracted from cells growing exponentially in rich medium showed that the three ORFs are independently transcribed. hlyA is transcribed from two promoters separated by 10 base pairs (P1 hlyA and P2 hlyA). ORF U is transcribed in the opposite direction from an adjacent promoter. These two promoter regions are separated by a palindromic sequence T-T-A-A-C-A-A/T-T-G-T-T-A-A. This palindrome was also found upstream from the ORF D promoter, suggesting that all three genes are similarly regulated.

Amino Acid Sequence↗

Escherichia coli thymidylate kinase: molecular cloning, nucleotide sequence, and genetic organization of the corresponding tmk locus.

Thymidylate kinase (dTMP kinase; EC 2.7.4.9) catalyzes the phosphorylation of dTMP to form dTDP in both de novo and salvage pathways of dTTP synthesis. The nucleotide sequence of the tmk gene encoding this essential Escherichia coli enzyme is the last one among all the E. coli nucleoside and nucleotide kinase genes which has not yet been reported. By subcloning the 24.0-min region where the tmk gene has been previously mapped from the lambda phage 236 (E9G1) of the Kohara E. coli genomic library (Y. Kohara, K. Akiyama, and K. Isono, Cell 50:495-508, 1987), we precisely located tmk between acpP and holB genes. Here we report the nucleotide sequence of tmk, including the end portion of an upstream open reading frame (ORF 340) of unknown function that may be cotranscribed with the pabC gene. The tmk gene was located clockwise of and just upstream of the holB gene. Our sequencing data allowed the filling in of the unsequenced gap between the acpP and holB genes within the 24-min region of the E. coli chromosome. Identification of this region as the E. coli tmk gene was confirmed by functional complementation of a yeast dTMP kinase temperature-sensitive mutant and by in vitro enzyme assay of the thymidylate kinase activity in cell extracts of E. coli by use of tmk-overproducing plasmids. The deduced amino acid sequence of the E. coli tmk gene showed significant similarity to the sequences of the thymidylate kinases of vertebrates, yeasts, and viruses as well as two uncharacterized proteins of bacteria belonging to Bacillus and Haemophilus species.

Amino Acid Sequence↗

Transcription map of the B genome component of tomato golden mosaic virus and comparison with A component transcripts.

In a previous study, the bipartite genome of tomato golden mosaic virus (TGMV) was shown to be transcribed into at least six polyadenylated RNAs (G. Sunter, W.E. Gardiner, and D. M. Bisaro, 1989, Virology 170, 243-250). Two of these, a 1.3-kb complementary sense and a 0.9-kb viral sense transcript, were mapped to the B genome component of this geminivirus. The results of more detailed primer extension and S1 nuclease protection experiments presented here define the limits of the single transcription unit corresponding to the 0.9-kb RNA which spans the BR1 open reading frame (ORF). The data also demonstrate that complementary sense TGMV RNAs are more complex than indicated by our earlier studies. Analysis of the 1.3-kb BL1-specific RNA indicates that it is actually a family of distinct transcripts with different start sites. Three transcripts have 5' ends that map near the common region of DNA B and all of these start sites lie upstream of the BL1 ORF. Similar analysis of the 1.6-kb complementary sense AL1 RNA indicates that a complex set of transcripts also map to the analogous region of genome component A. Four transcripts have 5' ends that map near the common region but only one of these start sites is upstream of the initiation codon for the AL1 open reading frame (ORF). None of the transcripts appear to be processed. The possible significance of multiple transcripts in these regions of the TGMV genome is discussed, and the common region-proximal transcription units of the A and B genome components are compared.

Autoradiography↗

Regulation of hexuronate utilization in Bacillus subtilis.

We have identified a locus essential for galacturonate utilization in Bacillus subtilis. Genes homologous to Escherichia coli and Erwinia chrysanthemi glucuronate and galacturonate metabolic genes were found in a cluster consisting of 10 open reading frames (ORFs) in the B. subtilis chromosome. A mutant of B. subtilis containing a replacement of the second and third ORFs was unable to grow with galacturonate as its primary carbon source. Galacturonate induced expression from a sigmaA-dependent promoter, exuP1, located upstream from the first ORF. The eighth ORF in this cluster (the exu locus) encodes a LacI and GalR homolog that negatively regulated expression from exuP1. A 26-bp inverted repeat sequence centered 15 bp downstream from the exuP1 start point of transcription acted in cis to negatively regulate expression from exuP1 under noninducing conditions. Expression from the exuP1 promoter was repressed by high levels of glucose, which is probably mediated by CcpA (catabolite control protein A). A sigmaE-dependent promoter, exuP2, was localized between the second and third ORFs and was active during sporulation.

Aldose-Ketose Isomerases↗

Identification of two genes in the unique short region of pseudorabies virus; comparison with herpes simplex virus and varicella-zoster virus.

We have determined the nucleotide sequence of two genes in the unique short region of the genome of pseudorabies virus (PRV). Near the internal repeat, upstream of the gene encoding glycoprotein gX, we identified an open reading frame (ORF) encoding a protein of 390 amino acids. We designated this gene PK because the predicted protein contains most of the conserved motifs of a eukaryotic protein kinase. The protein shares amino acid homology with the protein kinases encoded by gene US3 of herpes simplex virus type 1 (HSV-1) and gene 66 of varicella-zoster virus. Near the terminal repeat, downstream of a gene encoding an 11K protein, we identified an ORF encoding a protein of 256 amino acids. We designated this gene 28K, the Mr of the predicted protein. Part of the amino acid sequence of 28K is homologous to the predicted US2 protein of HSV-1. Northern blot analysis revealed a 2.7 kb mRNA encoding the putative protein kinase and a 1.2 kb mRNA encoding the 28K protein in PRV-infected cells. The 5' ends of the mRNAs were mapped by primer extension. Two transcriptional start sites were identified for the PK mRNA: a minor start site immediately upstream of the ORF and a major start site (greater than 95% of the mRNA) within the ORF, 64 nucleotides upstream of an internal ATG codon. A single transcriptional start site was identified for the 28K mRNA immediately upstream of the ORF. Immunoblot analysis with anti-peptide sera revealed that, in cells infected with PRV, the PK gene was translated into two proteins with Mrs of 53K and 41K, and the 28K gene into a single protein with an Mr of 28K.

Amino Acid Sequence↗

Vaccinia virus gene A36R encodes a M(r) 43-50 K protein on the surface of extracellular enveloped virus.

A characterization of vaccinia virus strain Western Reserve (WR) open reading frame (ORF) A36R is described. This ORF is predicted to encode a 221-amino-acid protein (M(r) 25.1 K) with an amino-terminal hydrophobic sequence, seven potential sites for attachment of N-linked carbohydrate, but no carboxy-terminal transmembrane anchor. It is identical in vaccinia strain Copenhagen and shares 94.6% amino acid identity with the corresponding ORF in variola virus strains Harvey, India-1967, and Bangladesh-1975. RNA analyses detected a 600-nucleotide, early transcript that initiated 10-13 nucleotides upstream of the A36R ORF, and heterogeneously sized late transcripts running across the ORF. A rabbit antiserum raised against an Escherichia coli glutathione S-transferase fusion protein identified M(r) 43-50 K proteins that accumulated late during vaccinia virus infection and fractionated as integral membrane proteins during Triton X-114 partitioning. Similar polypeptides were expressed by vaccinia virus strains Tian Tan, Tashkent, Lister, Wyeth, Copenhagen, and IHD-J and by rabbitpox virus and cowpox virus (strain Brighton Red). Immunoblot analysis of purified and protease-digested intracellular mature virus (IMV) and extracellular enveloped virus (EEV) showed that the A36R proteins were present on the surface of EEV with type II membrane topology, but were absent from IMV. A WR deletion mutant lacking the A36R ORF (delta A36R) had a small plaque phenotype on all cell lines tested. IMV formation by delta A36R was unaltered but EEV formation was reduced approximately fivefold compared to wild-type (WT) when measured either by density gradient analysis of isotopically labeled virions or by infectivity assays. Thus the loss of the A36R protein from the EEV surface did not reduce EEV specific infectivity in vitro. Despite this, delta A36R showed striking attenuation compared with WT in a murine intranasal model. Finally, a revertant virus in which the A36R ORF was restored showed WT plaque size, EEV formation, and virulence, demonstrating that all the phenotypic differences of delta A36R were attributable to loss of the A36R gene and not to other mutations acquired during its construction.

Amino Acid Sequence↗

Cloning and sequencing of a secY homolog from Streptomyces scabies.

The complete DNA sequence of the Streptomyces scabies (Ss) secY homolog and partial sequences of adjacent upstream and downstream open reading frames (ORFs) have been determined. The nucleotide sequence of a 2-kb region predicts a polypeptide of 437 amino acids in length with homology to the SecY protein family. The Ss secY homolog lies upstream from a sequence that has homology to the adenylate kinase gene (adk) family. The translational stop codon of the putative SecY ORF overlaps the predicted start codon for the Adk ORF. Another ORF that lies upstream from the secY homolog has sequence similarity to the genes that code for the L15 r-protein. Within the 243-bp intergenic region between the L15 and SecY coding sequences, the presence of a streptomycete-like promoter sequence and an 18-bp inverted repeat suggests that the secY homolog and the adjacent downstream sequences may be transcribed independently of the L15 coding sequence. Transcript analysis indicates that the secY homolog is expressed in both Ss and Streptomyces lividans. The proposed gene and transcript organization of the L15-SecY-Adk coding regions in the Ss clone resembles that of Micrococcus luteus which, like the streptomycetes, has a G+C-rich genome.

Adenylate Kinase↗

A Drosophila gene encoding multiple splice variants of Kazal-type serine protease inhibitor-like proteins with potential destinations of mitochondria, cytosol and the secretory pathway.

A Drosophila gene (KAZ1), mapped to cytological position 61A1-2 on chromosome 3, has been cloned and found to encode multiple splice variants of Kazal-type serine protease inhibitor-like proteins. KAZ1 consists of five exons and four alternatively retained introns to produce six transcripts of type AB, C1, C2, C3, D and E. The AB transcript contains two ORFs, of which the upstream one produces a polypeptide alpha, which has a mitochondrial sorting signal. Localization to mitochondria was confirmed by expression in COS1 cells. The downstream ORF is shared partially with type C1, C2, C3, D and E transcripts and produces polypeptides beta, gamma, delta and epsilon when expressed in Drosophila cells. Type C1, C2 and C3 transcripts differ only in the 5'-noncoding sequence and thus all produce type gamma. Polypeptides gamma and epsilon have a signal sequence at their N-termini and are secreted into the medium while beta and delta lack this sequence and remain in the cytoplasm. Isoforms beta and epsilon share a common C-terminal sequence distinct from that shared by polypeptides gamma and delta. The N-terminal sequences of isoforms beta to epsilon contain a PEST region which could induce rapid intracellular degradation of isoforms beta and delta. Sequence analysis of the Kazal-type domain suggests a similar folding pattern as observed for rhodniin and SPARC/BM-40. Northern analysis and in situ hybridization showed that the type C3 transcript is predominant and the expression is highest in midgut at larval stage.

Amino Acid Sequence↗

The p10 gene of Spodoptera littoralis nucleopolyhedrovirus: nucleotide sequence, transcriptional analysis and unique gene organization in the p10 locus.

The p10 gene of the Spodoptera littoralis (Spli) multicapsid nucleopolyhedrovirus (MNPV) was identified. With a coding sequence of 315 nucleotides (nt), corresponding to a protein of 104 amino acids, the SpliMNPV p10 gene is the longest p10 gene known. This gene codes for a putative protein with an Mr of 11130 and was found to be most closely related to the Spodoptera exigua (Se) MNPV p10 (49.4% amino acid identity) and most distant from the Autographa californica (Ac) MNPV p10 (20.0% amino acid identity). Characterization of the protein's secondary structure and a comparison with other p10 protein species suggested that this p10 has an extended alpha-helical domain with high probability of forming a large coiled-coil structure. The p10 mRNA was about 1500 nt long, as determined by Northern blot analysis. Primer extension assay mapped three transcription start sites to a conserved baculovirus late promoter motif, TAAG. In the SpliMNPV genome, the p10 gene is not flanked by genes similar to p26 and p74, as found in SeMNPV, AcMNPV, Choristoneura fumiferana MNPV and Orgyia pseudotsugata MNPV. Instead, an open reading frame (ORF) of 945 bp is located downstream from the p10 gene and is followed by another ORF in opposite orientation, encoding the p74 protein. Upstream of the p10 sequences, an ORF of 552 bp was identified that potentially encodes a 184 amino acid protein of Mr 20925, which showed 52.2% identity with the encoded product of the SeMNPV xb187 gene.

Amino Acid Sequence↗

Identification and characterization of a bile acid 7alpha-dehydroxylation operon in Clostridium sp. strain TO-931, a highly active 7alpha-dehydroxylating strain isolated from human feces.

Clostridium sp. strain TO-931 can rapidly convert the primary bile acid cholic acid to a potentially toxic compound, deoxycholic acid. Mixed oligonucleotide probes were used to isolate a gene fragment encoding a putative bile acid transporter from Clostridium sp. strain TO-931. This DNA fragment had 60% nucleotide sequence identity to a known bile acid transporter gene from Eubacterium sp. strain VPI 12708, another bile acid-7alpha-dehydroxylating intestinal bacterium. The DNA (9.15 kb) surrounding the transporter gene was cloned from Clostridium sp. strain TO-931 and sequenced. Within this larger DNA fragment was a 7.9-kb region, containing six successive open reading frames (ORFs), that was encoded by a single 8.1-kb transcript, as determined by Northern blot analysis. The gene arrangement and DNA sequence of the Clostridium sp. strain TO-931 operon are similar to those of a Eubacterium sp. strain VPI 12708 bile acid-inducible operon containing nine ORFs. Several genes in the Eubacterium sp. strain VPI 12708 operon have been shown to encode products required for bile acid 7alpha-dehydroxylation. In Clostridium sp. strain TO-931, genes potentially encoding bile acid-coenzyme A (CoA) ligase, 3alpha-hydroxysteroid dehydrogenase, bile acid 7alpha-dehydratase, bile acid-CoA hydrolase, and a bile acid transporter were similar in size and exhibited amino acid homology to similar gene products from Eubacterium sp. strain VPI 12708 (encoded by baiB, baiA, baiE, baiF, and baiG, respectively). However, no genes similar to Eubacterium sp. strain VPI 12708 biaH or baiI were found in the Clostridium sp. strain TO-931 bai operon, and the two putative Eubacterium sp. strain VPI 12708 genes, baiC and baiD, were arranged in one continuous ORF in Clostridium sp. strain TO-931. Intergene regions showed no significant DNA sequence similarity, but primer extension analysis identified a region 115 bp upstream from the first ORF that exhibited 58% identity to a bai operator/promoter region identified in Eubacterium sp. strain VPI 12708. These results indicate that the gene organization, gene product amino acid sequences, and promoters of the bile acid-inducible operons of Clostridium sp. strain TO-931 and Eubacterium sp. strain VPI 12708 are highly conserved.

3-Hydroxysteroid Dehydrogenases↗

Identification and cloning of an Erwinia carotovora subsp. carotovora bacteriocin regulator gene by insertional mutagenesis.

Avirulent Erwinia carotovora subsp. carotovora CGE234-M403 produces two types of bacteriocin. For the purpose of cloning the bacteriocin genes of strain CGE234M403, a spontaneous rifampin-resistant mutant of this strain, M-rif-11-2, was isolated. By Tn5 insertional mutagenesis using M-rif-11-2, a mutant, TM01A01, which produces the high-molecular-weight bacteriocin but not the low-molecular-weight bacteriocin was obtained. By thermal asymmetric interlaced PCR, the DNA sequence from the Tn5 insertion site and the DNA sequence of a contiguous 1,280-bp region were determined. One complete open reading frame (ORF), designated ORF2, was identified within the sequenced fragment. The 3' end of another ORF, ORF1, was located upstream of ORF2. A noncoding region and a putative promoter were located between ORF1 and ORF2. Downstream from ORF2, the 5' end of another ORF (ORF3) was found. Deduction from the nucleotide sequence indicated that ORF2 encodes a protein of 99 amino acids, which showed high homology with Yersinia enterocolitica Yrp, a regulator of enterotoxin (Y-ST) production; Escherichia coli host factor 1, required for Qbeta-replicase; and Azorhizobium caulinodans NrfA, required for the expression of nifA. ORF2 was designated brg, bacteriocin regulator gene. A fragment containing ORF2 and its promoter was amplified and cloned into pBR322 and pHSG415r, and the recombinant plasmids, pBYL1 and pHYL1, were transferred into E. coli DH5. Plasmid pBYL1 was reisolated and transferred into the insertion mutant TM01A01. Transformants carrying the plasmid, which was reisolated and designated pBYL1, re-produced the low-molecular-weight bacteriocin.

Amino Acid Sequence↗

Functional properties of an alternative, tissue-specific promoter for human arylamine N-acetyltransferase 1.

Variable expression of human arylamine N-acetyltransferase 1 (NAT1) due to genetic polymorphism, gene regulation or environmental influences is associated with individual susceptibility to various cancers. Recent studies of NAT1 transcription showed that most mRNAs originate at a promoter, P1, located 11.8 kb upstream of the single open reading frame (ORF) exon. We have now characterized an alternative NAT1 promoter lying 51.5 kb upstream of the NAT1 ORF. In the present study, analysis of human RNAs representing 27 tissue types by reverse transcriptase-polymerase chain reaction (RT-PCR) and quantitative RT-PCR showed the upstream 51.5 kb promoter, designated P3, to be most active in specific tissues, including kidney, liver, lung, and trachea. All NAT1 P3 mRNAs included 5'-untranslated region (5'-UTR) internal exons of 61 and 175 nucleotides in addition to the 79 nucleotide 5'-UTR exon present in P1 mRNA. CAP-dependent amplification of 5'-P3 mRNA termini defined an 84 bp transcription start region in which most start sites are centrally clustered. The hepatoma-derived HepG2 cell line expressed a high level of P3 mRNA with the same spliced structure and start site pattern as found in normal tissues. A 435-bp minimal promoter was defined by transfection of HepG2 with luciferase expression constructs containing genomic fragments from the P3 start region. These findings imply a fundamental role for P3 in NAT1 regulation and define additional regions for genetic polymorphisms associated with enhanced cancer risk.

Arylamine N-Acetyltransferase↗

Nucleotide Sequence of a 4 730 Base Pairs Region of the Spodoptera litura Nucleopolyhedrovirus Genome.

A 4 730 bp region of the Spodoptera litura Nucleopolyhedrovirus genome EcoRI-E fragment was sequenced, in which the odv-e66 gene and other two ORFs, ORF 1086 and the p34 gene, were found. The SpltNPV odv-e66 gene open reading frame was deduced to be 2 079 bp, encoding a protein of 692 amino acids. Unlike odv-e66 genes of AcMNPV and LsNPV, only one transcriptional initiation conserved sequence ATAAG of the late gene was present upstream of the initial codon ATG of SpltNPV odv-e66 gene, and no poly(A) signal was detected at the 3' end of the gene. Four highly conserved regions homologous to those of LdNPV, LsNPV, AcMNPV, BmNPV, CfNPV and OpNPV were present in the amino acid sequence of SpltNPV ODV-E66 protein, with the putative nuclear targeting signal(NTS) KKIWAEDGR in the fourth conserved region. The ORF upstream of the odv-e66 gene had the same direction of odv-e66 gene, but different reading frame. Besides the CAAT box, the early gene regulatory element ACGT and GC motifs and the transcriptional initiation conserved sequence TTAAG of the late gene were present at the 5' end of this ORF. A putative protein of 289 amino acid residues with Mr. about 34 kD was encoded by the ORF, so that it is named P34 protein. A leucine zipper and a leucine zipper-like structure were found in the C- and N-termini of SpltNPV P34 protein respectively. The functions of those regulatory elements may be of great importance to SpltNPV genome. An 1 086 nt open reading frame (ORF) capable of encoding a 361 amino acids polypeptide was found at the 3' end of the odv-e66 gene and in opposite direction. The ORF 1086 protein shares 44% amino acid sequence homology with AcMNPV ORF 109.

Journal Article↗

The vaccinia virus A14.5L gene encodes a hydrophobic 53-amino-acid virion membrane protein that enhances virulence in mice and is conserved among vertebrate poxviruses.

A short sequence, located between the A14L and A15L open reading frames (ORFs) of vaccinia virus, was predicted to encode a hydrophobic protein of 53 amino acids that is conserved in orthopoxviruses, leporipoxviruses, yatapoxiruses, and molluscipoxviruses. We constructed a recombinant vaccinia virus with a 10-codon epitope tag appended to the C terminus of the A14.5L ORF. Synthesis of the tagged protein occurred at late times and was blocked by an inhibitor of DNA replication, consistent with regulation by a predicted late promoter just upstream of the A14.5L ORF. Hydrophobicity of the protein was demonstrated by extraction into the detergent phase of Triton X-114. The protein was associated with purified vaccinia virus particles and with membranes of immature and mature virions that were visualized by electron microscopy of infected cells. Efficient release of the protein from purified virions occurred after treatment with a nonionic detergent and reducing agent. A mutant virus, in which the A14.5L ORF was largely deleted, produced normal-size plaques in several cell lines, and the yields of infectious intra- and extracellular viruses were similar to those of the parent. In contrast, with a mouse model, mutant viruses with the A14.5L ORF largely deleted were attenuated relative to that of the parental virus or a mutant virus with a restored A14.5L gene.

Amino Acid Sequence↗

Bacteriophage T4 encodes an RNase H which removes RNA primers made by the T4 DNA replication system in vitro.

RNase H activity increases markedly after bacteriophage T4 infection of Escherichia coli MIC2003, an RNase H-deficient host. We have extensively purified the RNase H from these T4-infected cells and have shown that the RNase H activity copurifies with a 5' to 3' DNA exonuclease activity. The N-terminal sequence of a 35-kDa protein copurifying with the RNase H activity matches the terminus of the predicted product of an open reading frame (designated ORF A or 33.2) upstream of T4 gene 33, identified previously by Hahn and co-workers (Hahn, S., Kruse, U., and Rüger, W. (1986) Nucleic Acids Res. 14, 9311-9327). Plasmids containing ORF A under the control of the T7 promoter express RNase H and 5' to 3' DNA exonuclease activities as well as a protein that comigrates on sodium dodecyl sulfate-polyacrylamide gels with the 35-kDa protein present in the RNase H purified from T4-infected cells. T4 RNase H removes the pentamer RNA primers from DNA chains initiated by the T4 primase-helicase (gene products 61 and 41). Addition of T4 RNase H and T4 DNA ligase leads to extensive joining of discontinuous lagging strand fragments in the T4 DNA replication system in vitro.

Amino Acid Sequence↗

Insertion of sequences containing the coat protein subgenomic RNA promoter and leader in front of the tobacco mosaic virus 30K ORF delays its expression and causes defective cell-to-cell movement.

The regulation of the internal open reading frame (ORF) of tobacco mosaic virus (TMV) that encodes the 30K movement protein was examined by constructing mutants in vitro with the putative coat protein subgenomic RNA promoter and leader sequences inserted upstream of the 30K ORF. A mutant with a 49-nucleotide fragment of the promoter region inserted replicated only transiently before being overtaken by a progeny wild-type virus with the insert deleted. A mutant with a 253-nucleotide promoter region fragment inserted replicated stably, and the inserted promoter was active in its new location. The production of 30K protein was not enhanced by this promoter/leader insertion to a level similar to that of coat protein. However, the accumulation of 30K protein was delayed, suggesting that different promoters/leader sequences determine the time of expression of the genes. This mutant was deficient in movement. A similar mutant, but with increased production of 30K protein, overcame the movement deficiency, suggesting that 30K protein is needed during the early stages of infection for efficient cell-to-cell movement of the virus.

Base Sequence↗

Nucleotide sequence and characterization of the 39K gene region of Autographa californica nuclear polyhedrosis virus.

The complete nucleotide sequence of the Pstl-K fragment of the Autographa californica nuclear polyhedrosis virus (AcMNPV) genome was determined. This region of the genome contains the delayed early 39K gene and V-ubi, a viral protein with homology to ubiquitine. In addition, Pstl-K potentially encodes five other proteins. Hybrid-select translation mapped nine viral-specific proteins to this fragment. Three proteins were observed with both early and late RNA; two of them comigrated with proteins directed by transcripts made from the 39K open reading frame (ORF). One protein which was only seen with hybrid-selected late RNA comigrated with ubiquitin. A correction of previously published sequence data indicates that there is an additional AUG codon upstream of the 39K ORF. This AUG codon is located 8 nucleotides downstream of the early transcription initiation site. The methionine codon is followed by codons for three amino acids and a termination codon. The 39K ORF is located 102 nucleotides downstream of the minicistron. In vitro transcription-translation experiments confirmed that the downstream AUG serves as the initiation codon for the 39K ORF. Radioimmunoprecipitation experiments indicated that the Pstl-K-encoded 39K protein reacted with antiserum raised against a previously described nuclear matrix-associated 39K protein.

Amino Acid Sequence↗

Mercury resistance in Bacillus cereus RC607: transcriptional organization and two new open reading frames.

The chromosomal mercury resistance determinant of Bacillus cereus RC607 confers resistance to inorganic mercury and to organomercurials. The order of genes in the completed mercury resistance determinant is operator-promoter 1 (O/P1) merR1 merT open reading frame 3 (ORF3) ORF4 merA O/P2 merR2 merB2 merB1. The previously undetermined 1-kb DNA sequence between the merA and merB1 genes includes two significant ORFs, whose predicted protein products are homologous with MerR (the transcriptional regulator) and MerB (the organomercurial lyase enzyme). Two transcriptional start sites (promoters), O/P1 at the beginning of the determinant and O/P2 immediately upstream of the sixth ORF, the newly identified merR2, were mapped by reverse transcriptase (RT) primer extension. A long 6.3-kb mRNA traversing all eight ORFs was shown by RT-PCR. Growth sensitivity measurements in liquid media and cellular mercury volatization assays characterized inducibility and differences in functional activity in B. cereus RC607 and after cloning of the mer determinant into plasmids in Escherichia coli.

Amino Acid Sequence↗