title: Molecular cloning and characterization of two different cDNAs encoding the molecular chaperone Hsp90 in the oomycete Achlya ambisexualis.
abstract: The chaperone Hsp90 plays a key role in the maturation and activation of many 'client' proteins in eukaryotic cells. In the oomycete Achlya ambisexualis two populations of hsp90 transcripts that differ slightly in size (2.8 and 2.9 kb) are present in heat-shocked mycelia. Only the 2.8 kb transcripts are seen in vegetative mycelia and in mycelia undergoing antheridiol-induced differentiation. Two different hsp90 cDNAs were isolated and characterized. Although nearly identical, an additional eight nucleotide sequence was present at the end of the 3'UTR of one of the two cDNAs. RT-PCR analyses indicated that hsp90 transcripts containing the eight nucleotide extension, were present only in heat-shocked mycelia. Hsp90 transcripts lacking this sequence were present in vegetative mycelia and the levels of these transcripts increased in both heat-shocked and hormone-treated mycelia. Each hsp90 cDNA encoded a nearly identical Hsp90 protein. However, two Hsp90 proteins (86 and 84 kDa) were observed on immunoblots of mycelial proteins. Only one of these, i.e., the 86 kDa protein was detected by an anti-phosphoserine antibody, suggesting that the difference in mass of the two Hsp90 isoforms, was due at least in part, to different levels of phosphoserine residues.
authors.affiliation: Department of Medical Genetics and Microbiology and Department of Life Sciences, University of Toronto at Scarborough, Toronto, Ont., Canada M1C 1A4.
authors.forename: Shelley A
authors.initials: SA
authors.lastname: Brunt
authors.forename: Julie C
authors.initials: JC
authors.lastname: Silver
mesh_terms: D020413:3' Untranslated Regions; D044743:Achlya / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020418:Algal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005786:Gene Expression Regulation; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D025282:Mycelium / Q000235:genetics / Q000254:growth & development; D009690:Nucleic Acid Conformation; D010766:Phosphorylation; D010768:Phosphoserine / Q000032:analysis; D010840:Phytosterols / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013696:Temperature
chemical_list: D020413:3' Untranslated Regions; D020418:Algal Proteins; D018076:DNA, Complementary; D018841:HSP90 Heat-Shock Proteins; D010840:Phytosterols; D012333:RNA, Messenger; D010768:Phosphoserine; C002834:antheridiol