Biomedical subjects

Carlo Presutti

Publications and source records attributed to Carlo Presutti.

4 recordsLinked to original sources

PubMed2006

The position of yeast snoRNA-coding regions within host introns is essential for their biosynthesis and for efficient splicing of the host pre-mRNA.

Genomic location of sequences encoding small nucleolar RNAs (snoRNAs) is peculiar in all eukaryotes from yeast to mammals: most of them are encoded within the introns of host genes. In Saccharomyces cerevisiae, seven snoRNAs show this location. In this work we demonstrate that the position of snoRNA-coding regions with respect to splicing consensus sequences is critical: yeast strains expressing mutant constructs containing shorter or longer spacers (the regions between snoRNA ends and intron splice sites) show a drop in accumulation of U24 and U18 snoRNAs. Further mutational analysis demonstrates that altering the distance between the 3' end of the snoRNA and the branch point is the most important constraint for snoRNA biosynthesis, and that stable external stems, which are sometimes present in introns containing snoRNAs, can overcome the positional effect. Surprisingly enough, splicing of the host introns is clearly affected in most of these constructs indicating that, at least in S. cerevisiae, an incorrect location of snoRNA-coding sequences within the host intron is detrimental to the splicing process. This is different with respect to what was demonstrated in mammals, where the activity of the splicing machinery seems to be dominant with respect to the assembly of snoRNPs, and it is not affected by the location of snoRNA sequences. We also show that intronic box C/D snoRNA recognition and assembly of snoRNPs occur during transcription when splicing sequences are recognized.

Introns↗

PubMed2006

Non coding RNA and brain.

Small non coding RNAs are a group of very different RNA molecules, present in virtually all cells, with a wide spectrum of regulatory functions which include RNA modification and regulation of protein synthesis. They have been isolated and characterized in all organisms and tissues, from Archaeobacteria to mammals. In mammalian brain there are a number of these small molecules, which are involved in neuronal differentiation as well as, possibly, in learning and memory. In this manuscript, we analyze the present knowledge about the function of the most important groups of small non-coding RNA present in brain: small nucleolar RNAs, small cytoplasmic RNAs, and microRNAs. The last ones, in particular, appear to be critical for dictating neuronal cell identity during development and to play an important role in neurite growth, synaptic development and neuronal plasticity.

Animals↗

PubMed2002

Enteroinvasive Escherichia coli virulence-plasmid-carried apyrase (apy) and ospB genes are organized as a bicistronic operon and are subject to differential expression.

In Shigella flexneri and enteroinvasive Escherichia coli (EIEC) the expression of the virulence-plasmid(pINV)-carried potential pathogenesis-associated apy gene, which encodes apyrase (ATP diphosphohydrolase), is regulated by the same regulators that govern the expression of virulence genes. To understand the transcriptional organization of the apy gene, the authors sequenced an 8023 bp PstI fragment of the pINV of EIEC strain HN280, which encompasses apy as well as its adjacent genes. The PstI fragment displays 99% identity with the corresponding fragment of pWR100, the pINV of S. flexneri strain M90T, and contains four genes. One of these genes, ospB, encodes a secreted protein of unknown activity and is located immediately upstream of apy. Analyses of sequence, Northern hybridization, RT-PCR and primer extension data and transcriptional fusions indicated that ospB and apy are co-transcribed as a 2 kb bicistronic, temperature-regulated mRNA from an upstream promoter that precedes ospB. The 2 kb mRNA is post-transcriptionally processed in the intercistronic ospB-apy region, leading to the considerable accumulation of a more stable 1 kb apy-specific mRNA (half-life of 2.2+/-0.3 min, versus 27+/-4 s for the 2 kb transcript). Upon temperature induction, peak expression of the ospB-apy operon occurs when bacteria enter into the late phases of bacterial growth, where the apy-specific transcript was found to be much more prevalent if compared to the ospB-apy transcript.

Apyrase↗

PubMed2002

Purified box C/D snoRNPs are able to reproduce site-specific 2'-O-methylation of target RNA in vitro.

Small nucleolar RNAs (snoRNAs) are associated in ribonucleoprotein particles localized to the nucleolus (snoRNPs). Most of the members of the box C/D family function in directing site-specific 2'-O-methylation of substrate RNAs. Although the selection of the target nucleotide requires the antisense element and the conserved box D or D' of the snoRNA, the methyltransferase activity is supposed to reside in one of the protein components. Through protein tagging of a snoRNP-specific factor, we purified to homogeneity box C/D snoRNPs from the yeast Saccharomyces cerevisiae. Mass spectrometric analysis demonstrated the presence of Nop1p, Nop58p, Nop56p, and Snu13p as integral components of the particle. We show that purified snoRNPs are able to reproduce the site-specific methylation pattern on target RNA and that the predicted S-adenosyl-L-methionine-binding region of Nop1p is responsible for the catalytic activity.

Binding Sites↗