Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two approaches were used to isolate fragments of chitin synthase genes from the opportunistic human pathogen Aspergillus fumigatus. Firstly, regions of amino acid conservation in chitin synthases of Saccharomyces cerevisiae were used to design degenerate primers for amplification of portions of related genes, and secondly, a segment of the S. cerevisiae CSD2 gene was used to screen an A. fumigatus lambda genomic DNA library. the polymerase chain reaction (PCR)-based approach led to the identification of five different genes, designated chsA, chsB, chsC, chsD and chsE. chsA, chsB, and chsC fall into Classes I, II and III of the 'zymogen type' chitin synthases, respectively. The chsD fragment has approximately 35% amino acid sequence identity to both the zymogen type genes and the non-zymogen type CSD2 gene. chsF appears to be a homologue of CSD2, being 80% identical to CSD2 over 100 amino acids. An unexpected finding was the isolation by heterologous hybridization of another gene (chsE), which also has strong sequence similarity (54% identity at the amino acid level over the same region as chsF) to CSD2. Reverse transcriptase-PCR was used to show that each gene is expressed during hyphal growth in submerged cultures.
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PMID:A multigene family related to chitin synthase genes of yeast in the opportunistic pathogen Aspergillus fumigatus. 785 20

The Colletotrichum graminicola tagged mutant T30 has conidia that burst and hyphal tips that swell in media with low osmotic pressure. The disrupted gene in T30 was identified as a class V chitin synthase (CSV) "chsA," which has an open reading frame of 1783 amino acids and two introns that are 52 and 54 bp. C. graminicola has one copy of chsA and no other highly homologous class V CHSs. Reverse transcriptase PCR indicated that the T30 mutant does not express the chsA transcript fragment in the conserved region in CSVs. Complementation of the mutant with chsA indicates that the encoded protein is responsible for approximately 29% of the chitin in conidial walls, is essential for conidial wall strength in media with high water potential and contributes to strength of hyphal tips. Analysis of the aligned deduced amino acid sequences of the 10 fully sequenced CSVs suggests that they are in two subgroups.
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PMID:A class V chitin synthase gene, chsA is essential for conidial and hyphal wall strength in the fungus Colletotrichum graminicola (Glomerella graminicola). 1268 17

The plant pathogenic fungus Magnaporthe grisea is able to enter its host via appressorium-mediated penetration. Earlier investigations have shown that these infection structures are rich in the cell wall polysaccharide chitin. Previously, we have described how the transcription of a class VII chitin synthase-encoding gene CHS7 is completely dependent on the putative transcription factor Con7p during the germination of conidia, and how con7(-) mutants are unable to form appressoria under any conditions tested. Because of the pleiotropic effects of the con7(-) mutation, we examined the consequences of the targeted deletion of CHS7. The chs7(-) mutants generated were unable to form appressoria on artificial surfaces, except following the application of the exogenous inducers 1,16-hexadecanediol and cyclic adenosine monophosphate. The appressoria formed had a reduced chitin content and were often found to be smaller and misshapen compared with the wild-type. chs7(-) mutants were significantly reduced in their ability to enter rice plants, but growth in planta was not affected. Reverse transcriptase-polymerase chain reaction analysis demonstrated that CHS7 transcription was strongly induced on germination of spores, and a green fluorescent protein-tagged Chs7p protein was found to be produced abundantly during infection-related morphogenesis. Together, these data suggest that the class VII chitin synthase Chs7p of M. grisea is required for normal appressorium formation and function.
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PMID:The Magnaporthe grisea class VII chitin synthase is required for normal appressorial development and function. 1916 55

The light-organ symbiosis of Euprymna scolopes, the Hawaiian bobtail squid, is a useful model for the study of animal-microbe interactions. Recent analyses have demonstrated that chitin breakdown products play a role in communication between E. scolopes and its bacterial symbiont Vibrio fischeri. In this study, we sought to determine the source of chitin in the symbiotic organ. We used a commercially available chitin-binding protein (CBP) conjugated to fluorescein to label the polymeric chitin in host tissues. Confocal microscopy revealed that the only cells in contact with the symbionts that labeled with the probe were the macrophage-like hemocytes, which traffic into the light-organ crypts where the bacteria reside. Labeling of extracted hemocytes by CBP was markedly decreased following treatment with purified chitinase, providing further evidence that the labeled molecule is polymeric chitin. Further, CBP-positive areas co-localized with both a halide peroxidase antibody and Lysotracker, a lysosomal marker, suggesting that the chitin-like biomolecule occurs in the lysosome or acidic vacuoles. Reverse transcriptase polymerase chain reaction (PCR) of hemocytes revealed mRNA coding for a chitin synthase, suggesting that the hemocytes synthesize chitin de novo. Finally, upon surveying blood cells from other invertebrate species, we observed CBP-positive regions in all granular blood cells examined, suggesting that this feature is a shared character among the invertebrates; the vertebrate blood cells that we sampled did not label with CBP. Although the function of the chitin-like material remains undetermined, its presence and subcellular location in invertebrate hemocytes suggests a conserved role for this polysaccharide in the immune system of diverse animals.
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PMID:The occurrence of chitin in the hemocytes of invertebrates. 2172 7