The lactose carrier of Klebsiella pneumoniae M5a1; the physiology of transport and the nucleotide sequence of the lacY gene.

A comparison has been made between the physiology and amino acid sequence of the lactose carriers of Klebsiella pneumoniae M5a1 and Escherichia coli K-12. The membrane transport of lactose was much weaker in Klebsiella than in E. coli. On the other hand o-nitrophenylgalactoside uptake by Klebsiella was distinctly greater than with E. coli. In spite of the differences in sugar transport between the two organisms, the amino acid sequences of the respective lactose carriers were remarkably similar (60% of the amino acids are identical).