当前位置： SCI文献检索 > JOURNAL OF BACTERIOLOGY期刊下所有文献 > Identification and sequence analysis of the Rhizobium meliloti dctA gene encoding the C4-dicarboxylate carrier.

Identification and sequence analysis of the Rhizobium meliloti dctA gene encoding the C4-dicarboxylate carrier.

Abstract：

:Transposon Tn5-induced C4-dicarboxylate transport mutants of Rhizobium meliloti 2011 which could be complemented by cosmid pRmSC121 were subdivided into two classes. Class I mutants (RMS37 and RMS938) were defective in symbiotic C4-dicarboxylate transport and in nitrogen fixation. They were mutated in the structural gene dctA, which codes for the C4-dicarboxylate carrier. Class II mutants (RMS11, RMS16, RMS17, RMS24, and RMS31) expressed reduced activity in symbiotic C4-dicarboxylate transport and in nitrogen fixation. These mutants were mutated in regulatory dct genes which do not play an essential role in the symbiotic state. Thin sections of alfalfa nodules induced by the wild type and class I and class II mutants were analyzed by light microscopy. Class mutants induced typical Fix- nodules, showing a large senescent zone, whereas nodules induced by class II mutants only differed in an enhanced content of starch granules compared with wild-type nodules. Class I mutants could be complemented by a 2.1-kilobase SalI-HindIII subfragment of cosmid pRmSC121. DNA sequencing of this fragment resulted in the identification of an open reading frame, which was designated dctA because Tn5 insertion sites of the class I mutants mapped within this coding region. The dctA gene was preceded by a nif consensus promoter and an upstream NifA-binding element. Upstream of the dctA promoter, the 5' end of the R. meliloti dctB gene could be localized. The amino acid sequence of the N-terminal part of the R. meliloti DctB protein shared 49% homology with the corresponding part of the R. leguminosarum DctB protein. The DctA protein consisted of 441 or 453 amino acids due to two possible ATG start codons, with calculated molecular masses of 46.1 and 47.6 kilodaltons, respectively. The hydrophobicity plot suggests that DctA is a membrane protein with several membrane passages. The amino acid sequences of the R. meliloti and the R. leguminosarum DctA proteins were highly conserved (82%).

journal_name

J Bacteriol

journal_title

Journal of bacteriology

authors

Engelke T,Jording D,Kapp D,Pühler A

doi

10.1128/jb.171.10.5551-5560.1989

subject

Has Abstract

pub_date

1989-10-01 00:00:00

pages

5551-60

issue

eissn

0021-9193

issn

1098-5530

journal_volume

171

pub_type

杂志文章

在线工具

Identification and sequence analysis of the Rhizobium meliloti dctA gene encoding the C4-dicarboxylate carrier.