Isolation and cloning of a Azospirillum lipoferum locus that complements Escherichia coli proU mutant

摘要

Glycine betaine relieved sodium chloride-mediated inhibition of growth in Azospirillum lipoferum ATCC 29708. S-35-methionine labelling of proteins after salinity up-shock revealed strong induction of a 30 kDa protein which cross-reacted with the anti-glycine betaine binding protein antibody from Escherichia coil. This suggested that A. lipoferum had a salinity-induced ProU-like high-affinity glycine betaine transport system. A genomic library of A. lipoferum ATCC 29708 was screened for the pro U-like gene by complementation of a Pro U mutant of E. coli. Four recombinant cosmids, capable of restoring growth of the proU mutant on plates containing 600 mM NaCl and 1 mM glycine betaine were selected. Selected recombinant cosmids hybridized with a proU gene probe from E. coli. Complementation of E. coli ProU mutant with the A. lipoferum genomic DNA was evident by the ability of proU mutant (containing selected recombinant cosmids) to grow on minimal medium supplemented with 600 mM NaCl and 1 mM glycine betaine. (C) 1998 Published by Elsevier Science B.V. [References: 21]