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J. Bacteriol., Jul 1995, 3721-3727, Vol 177, No. 13
Q Cheng, MC Yu, AR Reeves and AA Salyers
Bacteroides thetaiotaomicron can utilize a variety of polysaccharides,
including charged mucopolysaccharides such as chondroitin sulfate (CS) and
hyaluronic acid (HA). Since the enzymes (chondroitin lyases I and II) that
catalyze the first step in breakdown of CS and HA are located in the
periplasm, we had proposed that the first step in utilization of these
polysaccharides was binding to one or more outer membrane proteins followed
by translocation into the periplasm, but no such outer membrane proteins
had been shown to play a role in CS or HA utilization. Previously we have
isolated a transposon-generated mutant, CS4, which was unable to grow on CS
or HA but retained the ability to grow on disaccharide components of CS.
This phenotype suggested that the mutation in CS4 either blocked the
transport of the mucopolysaccharides into the periplasmic space or blocked
the depolymerization of the mucopolysaccharides into disaccharides. We have
mapped the CS4 mutation to a single gene, csuF, which is capable of
encoding a protein of 1,065 amino acids and contains a consensus signal
sequence. Although CsuF had a predicted molecular weight and pI similar to
those of chondroitin lyases, it did not show significant sequence
similarity to the Bacteroides chondroitin lyase II, a Proteus chondroitin
ABC lyase, or two hyaluronidases from Clostridium perfringens and
Streptococcus pyogenes, nor was any CS-degrading enzyme activity associated
with csuF expression in Bacteroides species or Escherichia coli. The
deduced amino acid sequence of CsuF exhibited features suggestive of an
outer membrane protein. We obtained antibodies to CsuF and demonstrated
that the protein is located in the outer membrane.(ABSTRACT TRUNCATED AT
250 WORDS)
Copyright © 1995, American Society for Microbiology
Identification and characterization of a Bacteroides gene, csuF, which encodes an outer membrane protein that is essential for growth on chondroitin sulfate
Department of Microbiology, University of Illinois, Urbana 61801, USA.
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