Assembly of a membrane receptor complex: Roles of the uroplakin II prosequence in regulating uroplakin bacterial receptor oligomerization

Chih Chi Andrew Hu, Thomas Bachmann, Ge Zhou, Feng Xia Liang, Jorge Ghiso, Gert Kreibich, Tung Tien Sun

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

The apical surface of the mammalian urothelium is almost completely covered by two-dimensional protein crystals (known as urothelial plaques) of hexagonally packed 16 nm particles consisting of two UP (uroplakin) heterodimers, i.e. UPs Ia/II and Ib/III pairs. UPs are functionally important as they contribute to the urothelial permeability barrier function, and UPIa may serve as the receptor for the uropathogenic Escherichia coli that causes over 90% of urinary tract infections. We study here how the UP proteins are assembled and targeted to the urothelial apical surface, paying special attention to the roles of the prosequence of UPII in UP oligomerization. We show that (i) the formation of the UPIa/UPII heterodimer, necessary for ER (endoplasmic reticulum) exit, requires disulfide formation in the prosequence domain of proUPII (the immature form of UPII still containing its prosequence); (ii) differentiation-dependent N-glycosylation of the prosequence leads to UP stabilization; (iii) a failure to form tetramers in cultured urothelial cells, in part due to altered glycosylation of the prosequence, may block two-dimensional crystal formation; and (iv) the prosequence of UPII remains attached to the mature protein complex on the urothelial apical surface even after it has been cleaved by the transGolgi-network-associated furin. Our results indicate that proper secondary modifications of the prosequence of UPII play important roles in regulating the oligomerization and function of the UP protein complex.

Original languageEnglish (US)
Pages (from-to)195-203
Number of pages9
JournalBiochemical Journal
Volume414
Issue number2
DOIs
StatePublished - Sep 1 2008

Keywords

  • Disulfide formation
  • Glycosylation
  • Integral membrane protein
  • Prosequence
  • Protein assembly
  • Uroplakin

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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