Analysis of the G93E mutant allele of KpsM, the membrane component of an ABC transporter involved in polysialic acid translocation in Escherichia coli K1

KpsM is an integral membrane protein involved in the translocation of the polysialic acid capsule of Escherichia coli K1. The kpsMG93E allele is a point mutation in the first cytoplasmic loop (CI) of KpsM which partially disrupts translocation of the capsule. While producing polymer of wild-type length, strains harboring the G93E allele exhibit a decreased production of capsular polymer and a reduced rate of polymer translocation to the cell surface.