PMID:9792691

Citation	Kihara, A and Ito, K (1998) Translocation, folding, and stability of the HflKC complex with signal anchor topogenic sequences. J. Biol. Chem. 273:29770-5
Abstract	HflK and HflC are plasma membrane proteins of Escherichia coli, each having a large C-terminal domain exposed to the periplasmic space and an N-terminally located transmembrane segment, which should act as a signal anchor sequence for their biogenesis. They form a complex, HflKC. We studied in vivo processes of biogenesis of this pair of membrane proteins. Translocation of the C-terminal domains across the membrane, as assessed by their accessibility to externally added protease, was completed within 1 min after the synthesis in wild-type cells as well as in the secB mutant cells or in the FtsY-depleted cells. 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. Thus, although targeting of these membrane proteins depends neither on the SecB chaperone nor on the SRP pathway, their translocation occurs exclusively via the Sec translocase complex. Translocated HflK molecules were then folded into a partially protease-resistant conformation, taking a few minutes, and this folding was induced upon association with HflC. Singly expressed HflK and HflC were unstable in vivo and periplasmic proteases DegP and Prc were involved in the degradation of the HflK subunit. We characterized several hflA alleles isolated in early studies; they alter the HflK or the HflC sequence and destabilize the HflKC complex.
Links	PubMed
Keywords	Amino Acid Sequence; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Biological Transport; Endopeptidase K/metabolism; Escherichia coli/metabolism; Molecular Sequence Data; Mutation; Protein Folding; Protein Sorting Signals/chemistry; Protein Sorting Signals/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOLI:HFLK	part_of	GO:0071575: integral component of external side of plasma membrane	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete
ECOLI:HFLC	part_of	GO:0071575: integral component of external side of plasma membrane	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete

References

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