Isolation and characterization of two chitinase-encoding genes (cts1, cts2) from the fungus Coccidioides immitis.
Two chitinase (CTS)-encoding genes (cts) from Coccidioides immitis (Ci), a respiratory fungal pathogen of humans, were cloned and sequenced. Both the genomic and cDNA sequences are presented. The transcription start points and poly(A)-addition sites were confirmed. The cts1 gene contains five introns and a 1281-bp ORF which translates a 427-amino-acid (aa) protein of 47.4 kDa. The cts2 gene contains two introns and a 2580-bp ORF which translates a 860-aa protein of 91.4 kDa. The deduced CTS1 protein showed highest homology to the Aphanocladium album and Trichoderma harzianum CTS (74% and 76%, respectively), while CTS2 showed highest homology to the CTS of Saccharomyces cerevisiae (Sc) and Candida albicans (47% and 51%, respectively). The putative N-terminal sequence of the mature CTS1 protein also showed 89% homology to the reported N-terminal sequence of a 48-kDa complement fixation antigen (CF-Ag) of Ci which has demonstrated chitinase activity. The CF-Ag is a clinically important antigen used in serodiagnosis of this fungal disease. CTS2 showed several of the conserved features of the Sc CTS, including putative catalytic and Ser/Thr-rich domains, and a C-terminal Cys-rich region. We propose that CTS1 and CTS2 of Ci are members of two distinct classes of fungal chitinases, an observation not previously reported for a single fungus.
Pishko
E J
EJ
Department of Botany, University of Texas, Austin 78713, USA.
Kirkland
T N
TN
Cole
G T
GT
D000595:Amino Acid Sequence; D001483:Base Sequence; D002688:Chitinases / Q000235:genetics*; D003001:Cloning, Molecular; D003045:Coccidioides / Q000201:enzymology / Q000235:genetics*; D017931:DNA Primers / Q000737:chemistry; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D002688:Chitinases