PMID:9712851

Citation	Akiyama, Y, Kihara, A, Mori, H, Ogura, T and Ito, K (1998) Roles of the periplasmic domain of Escherichia coli FtsH (HflB) in protein interactions and activity modulation. J. Biol. Chem. 273:22326-33
Abstract	FtsH is a membrane-bound and ATP-dependent protease of Escherichia coli, known to degrade SecY, a membrane protein for protein translocation, and CII, a soluble transcription factor for lysis/lysogeny decision of phage lambda. FtsH forms a homo-oligomeric complex as well as a hetero-oligomeric complex with HflKC, a putative modulator of FtsH. Although FtsH has a small periplasmic region, HflKC is mostly exposed to the periplasmic space. We studied the roles of the periplasmic region of FtsH by engineering mutations in this protein. FtsHDelta236, lacking most of the periplasmic region, retained the in vivo ability to degrade SecY but not CII, resulting in high frequency lysogenization of lambda. Several insertion mutations in the periplasmic region of FtsH also differentially affected the proteolytic activities of FtsH. Interestingly, purified and detergent-solubilized FtsHDelta236 was as active as the wild-type enzyme in degrading SecY and CII, although its ATPase activity was lowered 5-fold. Affinity chromatography using histidine-tagged derivatives showed that the periplasmic domain-deleted FtsH no longer interacted with FtsH or HflKC. Although FtsHDelta236-His6-Myc lost the static FtsH-FtsH interaction, it retained the ability to change its conformation in an ATP-dependent manner at 37 degreesC, leading to a limited oligomerization. These results suggest that the periplasmic region of FtsH has crucial roles in the protein-protein interactions of this complex and in the modulation of its proteolytic functions against different substrates.
Links	PubMed
Keywords	ATP-Dependent Proteases; Adenosine Triphosphatases/metabolism; Amino Acid Sequence; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Base Sequence; DNA Primers; Escherichia coli/growth & development; Escherichia coli/metabolism; Escherichia coli Proteins; Membrane Proteins/genetics; Membrane Proteins/metabolism; Molecular Sequence Data; Mutagenesis, Insertional; Periplasm/metabolism; Phenotype; Substrate Specificity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOBD:C5W9C5		GO:0006508: proteolysis	IDA: Inferred from Direct Assay:	P	Figure 2 shows in vivo degradation of the λCII protein	complete
ECOBD:C5W9C5		GO:0016021: integral to membrane	IDA: Inferred from Direct Assay:	C	Figure 5 shows impaired FtsH-FtsH interaction by a periplasmic deletion.	complete

References

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