Cc. Somerville et Rr. Colwell, SEQUENCE-ANALYSIS OF THE BETA-N-ACETYLHEXOSAMINIDASE GENE OF VIBRIO-VULNIFICUS - EVIDENCE FOR A COMMON EVOLUTIONARY ORIGIN OF HEXOSAMINIDASES, Proceedings of the National Academy of Sciences of the United Statesof America, 90(14), 1993, pp. 6751-6755
DNA cloned from the marine bacterium Vibrio vulnificus into Escherichi
a coli HB101 can hydrolyze chitin oligomer analogs in the recipient. T
he nucleotide sequence of the cloned DNA was determined and a single l
ong open reading frame of 2541 base pairs (initiation codon through te
rmination codon) was found. The nucleotide sequence predicts a gene pr
oduct of 847 amino acids and a molecular mass of 94.3 kDa. In vitro tr
anscription and translation analyses indicated a single protein of 94
kDa encoded by the cloned DNA. The gene product hydrolyzes methylumbel
liferyl beta-D Conjugates of chitotriose, chitobiose, N-acetylglucosam
ine, and N-acetylgalactosamine and has, therefore, been termed a beta-
N-acetylhexosaminidase. The predicted protein shares a high degree of
sequence similarity with the chitobiase of Vibrio harveyi and limited
similarity with the alpha chain of human beta-hexosaminidase. Cluster
analyses suggest a common evolutionary ancestor for all known hexosami
nidase enzymes, with no detectable relationship to known chitinases.