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Updated: Jul 17, 2026

Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43
Published on: September 11, 2020
Transformation in Streptococcus pneumoniae: formation of eclipse complex in a coiA mutant implicates CoiA in genetic
Bhushan V Desai1, Donald A Morrison
1Laboratory for Molecular Biology, Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA.
Abstract:
CoiA is a transient protein expressed specifically during competence and required for genetic transformation in Streptococcus pneumoniae, but not for DNA uptake. It is widely conserved among Gram-positive bacteria but its function is unknown. Here we report that although the rate of DNA uptake was not affected in a coiA mutant, the internalized donor DNA did not recombine into the host chromosome to form a physical and genetic heteroduplex. Instead, DNA taken up by a coiA mutant accumulated in the form of a single-stranded (ss) DNA-protein complex indistinguishable from the eclipse complex formed as a recombination intermediate in wild-type competent cells. Internalized donor DNA in a dprA mutant did not accumulate either as ss DNA or as an eclipse complex. Together, these results establish that a coiA mutant exhibits a phenotype different from that of dprA or recA mutants, and that CoiA functions at a later step in promoting recombination during genetic transformation in Streptococcus pneumoniae.
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