Second transmembrane segment of FtsH plays a role in its proteolytic activity and homo-oligomerization

Shin Ichi Makino, Tomohiro Makinoa, Kunitake Abe, Junko Hashimoto, Takashi Tatsuta, Masanari Kitagawa, Hirotada Mori, Teru Ogura, Tomoyuki Fujii, Shinya Fushinobu, Takayoshi Wakagi, Hiroshi Matsuzawa

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17 Citations (Scopus)


The FtsH (HflB) protein of Escherichia coli is a membrane-bound ATP- dependent zinc protease. The role(s) of the N-terminal membrane-anchoring region of FtsH were studied by fusion with a maltose-binding protein (MBP) at five different N-termini of FtsH. The MBP-FtsH fusions were expressed in the cytoplasm of E. coli, and were purified as soluble proteins. The four longer constructs, which have a second transmembrane segment and the C-terminal cytoplasmic region in common, retained ATP-dependent protease activity toward heat-shock transcription factor σ32, and were found to be homo-oligomers. In contrast, the shortest construct which has the C-terminal cytoplasmic region but not the second transmembrane segment showed neither protease activity nor oligomerization. Therefore, the second transmembrane segment, which neighbors the C-terminal cytoplasmic region of the FtsH, participates in not only its membrane-anchoring, but also its protease activity and homo- oligomerization.

Original languageEnglish
Pages (from-to)554-558
Number of pages5
JournalFEBS Letters
Issue number3
Publication statusPublished - 1999 Nov 5


  • AAA protein family
  • ATP-dependent protease
  • FtsH/HflB
  • Homo-oligomerization
  • Water-soluble MBP- FtsH fusion


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