Τίτλος:
Cloning, sequences, and characterization of two chitinase genes from the
antarctic Arthrobacter sp strain TAD20: Isolation and partial
characterization of the enzymes
Περίληψη:
Arthrobacter sp. strain TAD20, a chitinolytic gram-positive organism,
was isolated from the sea bottom along the Antarctic ice shell.
Arthrobacter sp. strain TAD20 secretes two major chitinases, ChiA and
ChiB (ArChiA and ArChiB), in response to chitin induction. A single
chromosomal DNA fragment containing the genes coding for both chitinases
was cloned in Escherichia coli. DNA sequencing analysis of this fragment
revealed two contiguous open reading frames coding for the precursors of
ArChiA (881 amino acids [aa]) and ArChiB (578 aa). ArChiA and ArChiB
are modular enzymes consisting of a glycosyl-hydrolase family 18
catalytic domain as well as two and one chitin-binding domains,
respectively. The catalytic domain of ArChiA exhibits 55% identity with
a chitodextrinase from Vibro furnissii. The ArChiB catalytic domain
exhibits 33% identity with chitinase A of Bacillus circulans. The
ArChiA chitin-binding domains are homologous to the chitin-binding
domain of ArChiB. ArChiA and ArChiB were purified to homogeneity from
the native Arthrobacter strain and partially characterized. Thermal
unfolding of ArChiA, ArChiB, and chitinase A of Serratia marcescens was
studied using differential scanning calorimetry. ArChiA and ArChiB,
compared to their mesophilic counterpart, exhibited increased heat
lability, similar to other cold-adapted enzymes.
Συγγραφείς:
Lonhienne, T
Mavromatis, K
Vorgias, CE
Buchon, L
Gerday,
C
Bouriotis, V
