Affiliation:
1. Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
Abstract
ABSTRACT
CpsA, CpsB, CpsC, and CpsD are part of a tyrosine phosphorylation regulatory system involved in modulation of capsule synthesis in
Streptococcus pneumoniae
and many other gram-positive and gram-negative bacteria. Using an immunoblotting technique, we observed distinct laddering patterns of
S. pneumoniae
capsular polysaccharides of various serotypes and found that transfer of the polymer from the membrane to the cell wall was independent of size. Deletion of
cps2A
,
cps2B
,
cps2C
, or
cps2D
in the serotype 2 strain D39 did not affect the ability to transfer capsule to the cell wall. Deletion of
cps2C
or
cps2D
, which encode two domains of an autophosphorylating tyrosine kinase, resulted in the production of only short-chain polymers. The function of Cps2A is unknown, and the polymer laddering pattern of the
cps2A
deletion mutants appeared similar to that of the parent, although the total amount of capsule was decreased. Loss of Cps2B, a tyrosine phosphatase and a kinase inhibitor, resulted in an increase in capsule amount and a normal ladder pattern. However, Cps2B mutants exhibited reduced virulence following intravenous inoculation of mice and were unable to colonize the nasopharynx, suggesting a diminished capacity to sense or respond to these environments. In D39 and its isogenic mutants, the amounts of capsule and tyrosine-phosphorylated Cps2D (Cps2D∼P) correlated directly. In contrast, restoration of type 2 capsule production followed by deletion of
cps2B
in Rx1, a laboratory passaged D39 derivative containing multiple uncharacterized mutations, resulted in decreased capsule amounts but no alteration in Cps2D∼P levels. Thus, a factor outside the capsule locus, which is either missing or defective in the Rx1 background, is important in the control of capsule synthesis.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
130 articles.
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