Expression pattern of Rhizobium etli ccmIEFH genes involved in c-type cytochrome maturation

Reyes, Josué David; Tabche, María-Luisa; Morera, Claudia; Girard, M.; Romero, David; Krol, Elizaveta; Miranda, J.; Soberón, Mário

doi:10.1016/s0378-1119(00)00176-1

Cited by 4 publications

(8 citation statements)

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“…These data confirm that strain PP2982 produces an N-terminal CycH subdomain, which is functionally active in the absence of the C-terminal part. The presence of active, functionally different, N-terminal subdomains has been demonstrated previously for CycH proteins in B. japonicum (Ritz et al 1993), R. capsulatus (Lang et al 1996), and R. etli (Reyes et al 2000), where mutations that leave the N-terminal subdomain intact (up to the periplasmic region of the protein) were found not to affect production of the cytochrome c 1 of the bc 1 complex. An increased level of PPIX was also detected in cyc mutant strains of R. leguminosarum (Yeoman et al 1997).…”

Section: Discussionsupporting

confidence: 61%

“…Mutations that eliminate the function of the N-terminal subdomain of the protein result in the lack of all known c-type cytochromes. However, mutants of R. capsulatus, B. japonicum and R. etli in which only the C-terminal region of CycH was deleted always produced cytochrome c 1 (Lang et al 1996;Ritz et al 1993;Reyes et al 2000).…”

Section: Introductionmentioning

confidence: 98%

“…They form a heme lyase complex which is involved in the covalent attachment of heme to apocytochrome c. Mutations in any of the cyc genes result in the loss of c-type cytochromes, and block symbiotic nitrogen fixation. Homologues of these genes have been described in several bacteria: the cycHJKL operon in Rhizobium leguminosarum (Delgado et al 1995), and B. japonicum (Ritz et al 1995); the ccmIEFH operon in Rhizobium etli (Reyes et al 2000); the genes cycH, ccl12 and cycJ in R. capsulatus (Lang et al 1996;Gabblert et al 1997;Deshmukh et al 2000); the ccmFH genes in Paracoccus denitrificans (Pearce et al 1998); and the ccmEF and ccmH genes in E. coli (Grove et al 1996). Although various direct protein-protein interactions between the subunits of the heme lyase complex have been detected (Ren et al 2002), the architecture of the complex is still unknown.…”

Section: Introductionmentioning

confidence: 99%

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The roles of different regions of the CycH protein in c-type cytochrome biogenesis in Sinorhizobium meliloti

et al. 2004

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Cytochrome c heme lyases encoded by the Sinorhizobium meliloti cycHJKL operon are responsible for generating the covalent bond between the heme prosthetic group and apocytochromes c. The CycH protein with its presumably membrane-associated N-terminal and periplasmic C-terminal parts is thought to be responsible for binding apocytochrome and presenting it to the heme ligation machinery. We propose that these two modules of CycH play roles in different functions of the protein. The N-terminal 96 amino acids represent an active subdomain of the protein, which is able to complement the protoporphyrin IX (PPIX) accumulation phenotype of the cycH mutant strain AT342, suggesting that it is involved in the final steps of heme C biosynthesis. Furthermore, three tetratricopeptide (TPR) domains have been identified in the C-terminal periplasmic region of the CycH protein. TPR domains are known to mediate protein-protein interactions. Each of these CycH domains is absolutely required for protein function, since plasmid constructs carrying cycH genes with in-frame TPR deletions were not able to complement cycH mutants for their nitrate reductase (Rnr-) and nitrogen-fixing (Fix-) phenotypes. We also found that the 309-amino acid N-terminal portion of the CycH, which includes all the TPR domains, is able to mediate the assembly of the c-type cytochromes required for the Rnr+ phenotype. In contrast, only the full-length protein confers the ability to fix nitrogen.

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Section: Discussionsupporting

confidence: 61%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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The roles of different regions of the CycH protein in c-type cytochrome biogenesis in Sinorhizobium meliloti

et al. 2004

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“…ccmIEFH is a complex operon encoding subunits of a heme-lyase. The ccmE gene encodes a heme chaperone shuttling heme between CcmC and CcmF; CcmH associates with CcmF and participates in keeping the apoprotein in a reduced state; CcmI functions as an assembly factor delivering apocytochrome to the heme ligation complex. , In some bacterial species such as Rhizobium etli and Rhodobacter capsulatus, ccmF could be transcribed independently from ccmI depending on different culture conditions. However, in other rhizobia such as S.…”

Section: Discussionmentioning

confidence: 99%

Copper Tolerance Mechanisms of Mesorhizobium amorphae and Its Role in Aiding Phytostabilization by Robinia pseudoacacia in Copper Contaminated Soil

Hao

Xie

Zhu

et al. 2015

Environ. Sci. Technol.

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The legume-rhizobium symbiosis has been proposed as an important system for phytoremediation of heavy metal contaminated soils due to its beneficial activity of symbiotic nitrogen fixation. However, little is known about metal resistant mechanism of rhizobia and the role of metal resistance determinants in phytoremediation. In this study, copper resistance mechanisms were investigated for a multiple metal resistant plant growth promoting rhizobium, Mesorhizobium amorphae 186. Three categories of determinants involved in copper resistance were identified through transposon mutagenesis, including genes encoding a P-type ATPase (CopA), hypothetical proteins, and other proteins (a GTP-binding protein and a ribosomal protein). Among these determinants, copA played the dominant role in copper homeostasis of M. amorphae 186. Mutagenesis of a hypothetical gene lipA in mutant MlipA exhibited pleiotropic phenotypes including sensitivity to copper, blocked symbiotic capacity and inhibited growth. In addition, the expression of cusB encoding part of an RND-type efflux system was induced by copper. To explore the possible role of copper resistance mechanism in phytoremediation of copper contaminated soil, the symbiotic nodulation and nitrogen fixation abilities were compared using a wild-type strain, a copA-defective mutant, and a lipA-defective mutant. Results showed that a copA deletion did not affect the symbiotic capacity of rhizobia under uncontaminated condition, but the protective role of copA in symbiotic processes at high copper concentration is likely concentration-dependent. In contrast, inoculation of a lipA-defective strain led to significant decreases in the functional nodule numbers, total N content, plant biomass and leghemoglobin expression level of Robinia pseudoacacia even under conditions of uncontaminated soil. Moreover, plants inoculated with lipA-defective strain accumulated much less copper than both the wild-type strain and the copA-defective strain, suggesting an important role of a healthy symbiotic relationship between legume and rhizobia in phytostabilization.

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“…The level of ␤-galactosidase was determined as described (20), by measuring the rate of hydrolysis of o-nitrophenyl-␤-D-galactopyranoside in cells permeabilized with SDS-CHCl 3 . All assays were performed in triplicate.…”

Section: Methodsmentioning

confidence: 99%

A conserved RNA structure ( thi box) is involved in regulation of thiamin biosynthetic gene expression in bacteria

Miranda-Ríos

Navarro²,

Soberón³

2001

Proc. Natl. Acad. Sci. U.S.A.

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226

153

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The thiCOGE genes of Rhizobium etli code for enzymes involved in thiamin biosynthesis. These genes are transcribed with a 211-base untranslated leader that contains the thi box, a 38-base sequence highly conserved in the 5 regions of thiamin biosynthetic and transport genes of Gram-positive and Gram-negative organisms. A deletion analysis of thiC-lacZ fusions revealed an unexpected relationship between the degree of repression shown by the deleted derivatives and the length of the thiC sequences present in the transcript. Three regions were found to be important for regulation: (i) the thi box sequence, which is absolutely necessary for high-level expression of thiC; (ii) the region immediately upstream to the translation start codon of thiC, which can be folded into a stem-loop structure that would mask the Shine-Dalgarno sequence; and (iii) the proximal part of the coding region of thiC, which was shown to contain a putative Rho-independent terminator. A comparative phylogenetic analysis revealed a possible folding of the thi box sequence into a hairpin structure composed of a hairpin loop, two helixes, and an interior loop. Our results show that thiamin regulation of gene expression involves a complex posttranscriptional mechanism and that the thi box RNA structure is indispensable for thiCOGE expression.T hiamin pyrophosphate (TPP), also known as cocarboxylase, is the cofactor of key enzymes of carbon metabolism such as pyruvate dehydrogenase, ␣-ketoglutarate dehydrogenase, transketolase, pyruvate decarboxylase, and others. TPP is made by the enzymatic coupling of two independently synthesized precursors, 4-amino-5-hydroxymethyl-2-methyl pyrimidine pyrophosphate and 5-(2-hydroxyethyl)-4-methyl thiazole monophosphate (1).In Escherichia coli and Salmonella enterica serovar Typhimurium, several genes are known to participate in TPP biosynthesis (2). thiC and thiD are required for 4-amino-5-hydroxymethyl-2-methyl pyrimidine pyrophosphate synthesis (3, 4), whereas dxs (5, 6), thiF, thiS, thiG, thiH, and thiI are involved in 5-(2-hydroxyethyl)-4-methyl thiazole monophosphate synthesis (3,7,8). In addition, the product of the thiE gene couples 4-amino-5-hydroxymethyl-2-methyl pyrimidine pyrophosphate and 5-(2-hydroxyethyl)-4-methyl thiazole monophosphate to give thiamin monophosphate, which undergoes another phosphorylation catalyzed by the product of the thiL gene to form TPP, the biologically active form of vitamin B 1 (9, 10). A salvage enzyme (thiamin kinase) encoded by thiK, which incorporates exogenous thiamin into TPP (11), also exists. In both organisms the thi genes are located throughout the chromosome and are arranged in three operons and four single gene loci (2). thiCEFSGH, thiMD (ThiM and ThiD are involved in salvage of 5-(2-hydroxyethyl)-4-methyl thiazole and 4-amino-5-hydroxymethyl-2-methyl pyrimidine from the culture medium, respectively; ThiD also catalyzes the phosphorylation of 4-amino-5-hydroxymethyl-2-methyl pyrimidine monophosphate and thiBPQ (which code for an ABC type transport system for t...

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Expression pattern of Rhizobium etli ccmIEFH genes involved in c-type cytochrome maturation

Cited by 4 publications

References 36 publications

The roles of different regions of the CycH protein in c-type cytochrome biogenesis in Sinorhizobium meliloti

The roles of different regions of the CycH protein in c-type cytochrome biogenesis in Sinorhizobium meliloti

Copper Tolerance Mechanisms of Mesorhizobium amorphae and Its Role in Aiding Phytostabilization by Robinia pseudoacacia in Copper Contaminated Soil

A conserved RNA structure ( thi box) is involved in regulation of thiamin biosynthetic gene expression in bacteria

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