Disease relevance of secD

• The secD operon of Escherichia coli is required for the efficient export of proteins [1].

High impact information on secD

• E. coli cells harboring pCG169 containing the secD secF locus possessed SecA protein almost entirely in an integral membrane form in which it displayed normal protein translocation activity [2].
• Mutations in secD and secF show impaired protein translocation across the inner membrane of Escherichia coli [3].
• Cold-sensitive mutations in the secD locus of Escherichia coli result in severe defects in protein export at the non-permissive temperature of 23 degrees C. DNA sequence of a cloned fragment that includes the secD locus reveals open reading frames for seven polypeptide chains [4].
• This kinetic analysis revealed that secB and secD mutants exhibit nearly identical defects in precursor translocation from the cytoplasm [5].
• The secD operon is not induced in response to either secretion defects or temperature changes [1].

Biological context of secD

• A plasmid carrying secD+ was identified and used to show that the mutations are recessive [6].
• After a shift to the nonpermissive temperature, the kinetics of accumulation of prolipoprotein and pre-OmpA protein was indistinguishable from that of pre-OmpA protein accumulation in the secD and secF mutants but different in the secE mutant [7].
• The secD gene is closely linked to tsx on the E. coli chromosome, but separable from another gene proposed to be involved in export, ssaD, which maps nearby [6].

Other interactions of secD

• Overexpression of "yajC", located within the secD operon, suppressed secY-d1 [8].
• The secD mutations fall into two complementation groups, defining genes we have named secD and secF [4].
• We also studied the phenotypes of strains in which one of the secY mutations was combined with the components of the secD operon [8].
• The prolipoprotein accumulated in the secD, secE, and secF mutants at the nonpermissive temperature was not modified with glyceride [7].

References