Membrane Biology

kao Yoshinori Akiyama, D. Sci, Professor  btn

Our research projects are concerned with post-translational events in the expression of genetic information. Specifically, processes of protein translocation across and integration into the membrane, membrane protein proteolysis and extracytoplasmic stress responses are investigated by combined molecular genetic, biochemical and structural approaches. Second group is studying the lifecycle of HPV and the molecular mechanism of the virus-induced tumor formation.

Research and Education

Protein Protein translocation across the membrane is mediated by the evolutionary conserved SecYEG complex, the motor protein SecA and the accessory membrane complex SecDF in Bacteria. Vibrio VemP acts to regulate expression of the down stream SecDF genes through its translational elongation arrest.
Proteolysis plays important roles not only in quality control but also in functional regulation of membrane proteins. We are interested in both these aspects. Also, we address the problem of how an E coli cell responds to the cell surface stresses caused by accumulation of abnormal membrane proteins.
HPV infection and the tumorigenesis: The HPV replication is strictly regulated by the differentiation program of the host cell. We are investigating the cross-talk between the virus and the host cell.

Fig. 1: Protein translocation/integration (left), extracytoplasmic stress response (center), and surface protein degradation (right) in Gram-negative bacteria.

Fig. 2: Ras activation conferred invasion potential to keratinocytes expressing high-risk type E7.

Recent Publications

  1. Yokoyama, T., Niinae, T., Tsumagari, K., Imami, K., Ishihama, Y., Hizukuri, Y., and Akiyama, Y. (2021) Escherichia coli S2P family intramembrane protease RseP is engaged in the regulated sequential cleavages of FecR in the ferric citrate signaling. J. Biol. Chem. in press
  2. Miyazaki, R., Akiyama, Y., and Mori, H. (2020) Fine interaction profiling of VemP and mechanisms responsible for its translocation-coupled arrest-cancelation. eLife 9, e62623.
  3. Miyake, T., Hizukuri, Y.*, and Akiyama, Y. (2020) Involvement of a membrane-bound amphiphilic helix in substrate discrimination and binding by an Escherichia coli S2P peptidase RseP. Front. Microbiol. 11, 607381.
  4. Daimon, Y., Narita, S., Miyazaki, R., Hizukuri, Y., Mori, H., Tanaka, Y., Tsukazaki, T., and Akiyama, Y. (2020) Reversible auto-inhibitory regulation of Escherichia coli metallopeptidase BepA for selective β-barrel protein degradation. Proc. Natl. Acad. Sci. USA 117, 27989-27996.
  5. Ueno, T., Sasaki, K., Yoshida, S., Kajitani, N., Satsuka, A., Nakamura, H. and Sakai, H. (2006) Molecular mechanisms of hyperplasia induction by human papillomavirus E7. Oncogene 25, 4155-4164


Professor:Yoshinori Akiyama
Associate professor:Hiroyuki Sakai, Hiroyuki Mori
Assistant professor:Yohei Hizukuri
TEL: +81-75-751-4040
FAX: +81-75-771-5699