Disease relevance of secA

• It was shown previously that the secA gene of Escherichia coli is derepressed in cells that have a defect in protein export [1].
• However, it did not complement the temperature-sensitive mutation in E. coli MM52 (SecAts) (a conditional lethal mutant defective in protein translocation) allowing only poor growth at the nonpermissive temperature. secA homologous sequences were present in 11 different species of Streptomyces and Nocardia [2].
• Cloning, expression, and functional characterization of the Mycobacterium tuberculosis secA gene [3].
• Membrane topology of the Rickettsia prowazekii ATP/ADP translocase revealed by novel dual pho-lac reporters [4].
• Functional and structural characterization of the minimal Sec translocase of the hyperthermophile Thermotoga maritima [5].

High impact information on secA

• The soluble and membrane components of an E. coli in vitro protein translocation system prepared from a secA amber mutant, secA13[Am], contain reduced levels of SecA and are markedly defective in both the cotranslational and posttranslational translocation of OmpA and alkaline phosphatase into membrane vesicles [6].
• FtsK is a DNA translocase that coordinates chromosome segregation and cell division in bacteria [7].
• The PrlA and PrlG phenotypes are caused by a loosened association among the translocase SecYEG subunits [8].
• In Escherichia coli, precursor proteins are translocated across the cytoplasmic membrane by translocase [9].
• In contrast, the lateral partitioning from translocase to lipids depends solely on temperature and does not require SecA ATP hydrolysis or SecA membrane cycling [10].

Chemical compound and disease context of secA

• The secA gene of S. lividans restored sensitivity to sodium azide in E. coli SecA4 (AzR) a mutant with an azide-resistant (ATPase defective) SecA protein [2].
• We optimized the codon usage for expression of tlc in Escherichia coli by means of gene synthesis, expressed the synthetic gene in E. coli, and purified a modified Tlc that contained a C-terminal tag of 10 consecutive histidine residues by immobilized metal affinity chromatography [11].
• The recent cloning of a human putative Glc-6-P carrier exhibiting homologies with bacterial phosphoester transporters, such as Escherichia coli UhpT (a Glc-6-P translocase), is compatible with the fact that two cysteine residues are important for the bacterial Glc-6-P transport [12].
• Affinity of TatCd for TatAd elucidates its receptor function in the Bacillus subtilis twin arginine translocation (Tat) translocase system [13].
• Using a continuous fluorescence-based enzyme assay, we have characterized the antibacterial agents tumicamycin and liposidomycin B as inhibitors of solubilized Escherichia coli phospho-N-acetylmuramyl-pentapeptide translocase [14].

Biological context of secA

• Since most suppressors of this toxic phenotype map to secA and secY, growth arrest results from a defective interaction of the chimeric protein with the export machinery [15].
• Nucleotide sequence of the secA gene and secA(Ts) mutations preventing protein export in Escherichia coli [16].
• It has an open reading frame encoding 841 amino acids (aa) with homology to the Escherichia coli secA gene, which is involved in protein secretion and cell separation [17].
• This open reading frame was followed by an additional open reading frame starting 59 base pairs further downstream and corresponded to the secA gene [18].
• SecM is expressed from the secM-secA operon and activates the expression of secA in response to secretion defects [19].

Anatomical context of secA

• In a cis-acting manner, ribosome stalling enhances secA translation [19].
• A processed form of maltose-binding protein (MBP) was detected in the spheroplasts of secY and secA temperature-sensitive mutant cells that had been pulse-labeled at the permissive temperature (30 degrees C) [20].
• Partial sequence analysis of the plastid DNA (ptDNA) from a red alga, Antithamnion sp., revealed the presence of a homologue to the Escherichia coli secA gene as well as two open reading frames (ORF 510, ORF 179) [21].
• Genetic complementation, mapping, and DNA sequence analysis now show that these mutations are alleles of the secA gene, which is essential for protein export across the E. coli plasma membrane [22].
• This indicates that cpSecE can functionally replace bacterial SecE in vivo, and strongly suggests that the thylakoid membrane contains a SecAYE-like translocase with functional and structural similarities to the bacterial complex [23].

Associations of secA with chemical compounds

• The export of these altered MBP species was also less affected in secA mutant cells and in cells treated with sodium azide [24].
• Secretion of methanol-insoluble heat-stable enterotoxin (STB): energy- and secA-dependent conversion of pre-STB to an intermediate indistinguishable from the extracellular toxin [25].
• Proteolytic conversion of pre-STB to STB was shown to be inhibited by the proton motive force uncoupler carbonyl cyanide m-chlorophenylhydrazone and did not occur in a secA background [25].
• The paradigm for the study of rickettsial transport systems is the ATP/ADP translocase Tlc1, which exchanges bacterial ADP for host cell ATP as a source of energy, rather than as a source of adenylate [26].
• Cysteine-scanning Mutagenesis and Disulfide Mapping Studies of the Conserved Domain of the Twin-arginine Translocase TatB Component [27].

Regulatory relationships of secA

• Mutations previously designated prlD were described that suppressed malE signal sequence mutations and were located in the vicinity of the secA gene on the Escherichia coli chromosome [28].

Other interactions of secA

• A mutation affecting the regulation of a secA-lacZ fusion defines a new sec gene [1].
• Using malE and phoA signal sequence mutants, we showed that the vast majority of these secA suppressors exhibit weak Sec phenotypes [29].
• secG and temperature modulate expression of azide-resistant and signal sequence suppressor phenotypes of Escherichia coli secA mutants [30].
• Transcription of envA and the upstream fts genes terminated at this terminator and was probably uncoupled from the downstream genes, including secA [18].
• SsrA tagging affected neither the presence of the secM mRNA nor secA expression, even under translocation-defective conditions [19].

Analytical, diagnostic and therapeutic context of secA

• Northern blot analysis revealed the presence of a truncated secM transcript, likely issued from a secM-secA cleavage [19].
• Functional complexity of the twin-arginine translocase TatC component revealed by site-directed mutagenesis [31].

References