Disease relevance of secY

• Escherichia coli prlA mutants (altered in the secY gene) are able to export cell envelope proteins lacking any signal sequence [1].
• Membrane insertion defects caused by positive charges in the early mature region of protein pIII of filamentous phage fd can be corrected by prlA suppressors [2].
• The chromosomal region encoding the secY gene of Streptomyces griseus N2-3-11 was cloned and analyzed [3].
• The secY gene of Vibrio cholerae has been cloned and the complete nt sequence determined [4].
• A conserved domain of the secY genes from Bacillus subtilis, Mycoplasma capricolum and Escherichia coli was used to design degenerate oligodeoxyribonucleotides [5].

High impact information on secY

• Evidence from gene fusions constructed in vitro suggests that prlA codes for a protein containing at least 300 amino acids [6].
• Combinations of certain prlA and prlG mutations, known to cause synthetic lethality in vivo, dramatically loosen subunit association and lead to complete disassembly of SecYEG [7].
• 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 [8].
• Suppressor mutations that alter SecY (the prlA alleles) broaden the specificity of this machinery and allow secretion of precursor proteins with defective signal sequences [9].
• We demonstrate that two exported proteins of E.coli, maltose-binding protein and alkaline phosphatase, each lacking its entire signal sequence, are exported to the periplasm in several prlA mutants [10].

Chemical compound and disease context of secY

• When expressed from the lac promoter, V. cholerae secY partially complements E. coli secY mutation even in absence of IPTG, while the E. coli secY gene complements only when IPTG is present [4].

Biological context of secY

• The phenotypes of temperature-sensitive and cold-sensitive mutations in secY suggest that the SecY protein plays an essential role in vivo to facilitate protein translocation, whereas the prlA mutations in this gene suggest that SecY may interact with the signal sequence of translocating polypeptides [11].
• The E. coli secY (prlA) gene, located in the operator-distal part of the spc ribosomal protein operon, codes for an integral membrane protein, SecY [11].
• We have now placed the secY, secE, and secG genes under the control of an arabinose-inducible promoter on a multicopy plasmid [12].
• Some secY mutations, including secY39, interfered with protein export when expressed from a multicopy plasmid, even in the presence of wild-type secY on the chromosome [13].
• We discuss the mechanism of prlA-mediated export and the role of the protein translocation apparatus in contributing to membrane protein topology [14].

Anatomical context of secY

• The secY (prlA) gene product is an essential component of the Escherichia coli cytoplasmic membrane, and its function is required for the translocation of exocytoplasmic proteins across the membrane [15].
• We report here on the retention of a secY gene in cyanelle (= plastid) DNA of the eukaryotic protist Cyanophora paradoxa [16].
• 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) [17].
• Membranes derived from secY ts cells which were incubated at 42 degrees C were inactive in vitro in the post-translational uptake and processing of pro-OmpA [18].

Associations of secY with chemical compounds

• The in vivo synthesis and export of plasmid-encoded MBP were studied in the presence and absence of isopropyl thiogalactoside and maltose and in a strain harboring a prlA mutation that suppresses the malE signal sequence mutation and is thought to alter the export machinery of cells [19].
• In contrast, translocation of these domains was retarded markedly when sodium azide was added to inhibit SecA ATPase and blocked almost completely in secY- or secD-defective mutant cells [20].
• A combination of this secY mutation and the secG deletion resulted in synthetic lethality, and the TM3 and TM4 SecY cysteine substitution mutations were examined for their ability to complement this lethality [21].
• Anhydrotetracycline-mediated induction of pKOR1-encoded secY antisense transcripts via the Pxyl/tetO promoter, a condition that is not compatible with staphylococcal growth, selects for chromosomal excision and loss of plasmid [22].

Other interactions of secY

• The allele-specific synthetic lethality of prlA-prlG double mutants predicts interactive domains of SecY and SecE [23].
• We also studied the phenotypes of strains in which one of the secY mutations was combined with the components of the secD operon [13].
• Our evidence indicates that the prlA and prlD gene products play an important role in the normal pathway for export of proteins to the cell envelope [24].
• We describe in this review recent results focusing on the function of the secA, secB, and secY gene products and the demonstration of their requirement for in vitro protein translocation [25].

Analytical, diagnostic and therapeutic context of secY

• Together with additional mutations generated by site-directed mutagenesis, a number of novel prlA mutations and/or suppressors were identified [26].
• Northern blot analysis revealed a growth phase-dependent secY expression supporting our previous findings for secA gene expression in S. griseus [3].
• Sequence analysis of the region surrounding rpoA identified six open reading frames that are found in the conserved gene order secY (SecY)-adk (Adk)-rpsM (S13)-rpsK (S11)-rpoA (alpha)-rplQ (L17) found in the alpha-proteobacteria [27].

References