Sequence Analysis of the exo1 Gene Involved in the Exopolysaccharide Synthesis of Rhizobium huakuii.
The 2.6 kb fragment which can complement the Exo(-)Ndv(-)Fix(-) mutants of R. huakuii to Exo(+)Nod(+)Fix(+) was sequenced. The result revealed the presence of an open reading frame exo1, which encodes 340 amino acids. Analysis of the hydrophobicity plot of the putative protein indicated that it was a cytoplasmic protein. Exo1 displayed strong homology to the ExoU protein of R. meliloti, which was a glucosyltransferase. A transcriptional fusion to lacZ using the promoterless vector pMP221 showed that there were two regions with promoter activity in exo1. Pexo1a was identified upstream of exo1, and Pexo1b in the middle of exo1. Pexo1a probably contains the promoter of exo1 gene.
Huang
Jian-Bin
JB
Shanghai Institute of Plant Physiology, the Chinese Academy of Sciences, Shanghai 200032, China.
Zhou
Bei-Yun
BY
Gong
Fong
F
Song
Hong-Yu
HY