Open AccessA Thioredoxin of Sinorhizobium meliloti CE52G Is Required for Melanin Production and Symbiotic Nitrogen Fixation
Author(s) -
Susana CastroSowinski,
Ofra Matan,
Paula Bonafede,
Yaacov Okon
Publication year - 2007
Publication title -
molecular plant-microbe interactions
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.565
H-Index - 153
eISSN - 1943-7706
pISSN - 0894-0282
DOI - 10.1094/mpmi-20-8-0986
Subject(s) - nitrogen fixation , sinorhizobium meliloti , thioredoxin , chemistry , melanin , nitrogen , biology , biochemistry , enzyme , organic chemistry
A miniTn5-induced mutant of a melanin-producing strain of Sinorhizobium meliloti (CE52G) that does not produce melanin was mapped to a gene identified as a probable thioredoxin gene. It was proved that the thiol-reducing activity of the mutant was affected. Addition to the growth medium of substrates that induce the production of melanin (l-tyrosine, guaiacol, orcinol) increased the thioredoxin-like (trxL) mRNA level in the wild-type strain. The mutant strain was affected in the response to paraquat-induced oxidative stress, symbiotic nitrogen fixation, and both laccase and tyrosinase activities. The importance of thioredoxin in melanin production in bacteria, through the regulation of laccase or tyrosinase activities, or both, by the redox state of structural or catalytic SH groups, is discussed.