4ZBH: THE CRYSTAL STRUCTURE OF THE SOLUBLE DOMAIN OF SULFOLOBUS ACIDOCALDARIUS FLAF

Citation:
Abstract
Archaea employ the archaellum, a type IV pilus-like nanomachine, for swimming motility. In the crenarchaeon Sulfolobus acidocaldarius, the archaellum consists of seven proteins: FlaB/X/G/F/H/I/J. FlaF is conserved and essential for archaellum assembly but no FlaF structures exist. Here, we truncated the FlaF N terminus and solved 1.5-A and 1.65-A resolution crystal structures of this monotopic membrane protein. Structures revealed an N-terminal alpha-helix and an eight-strand beta-sandwich, immunoglobulin-like fold with striking similarity to S-layer proteins. Crystal structures, X-ray scattering, and mutational analyses suggest dimer assembly is needed for in vivo function. The sole cell envelope component of S. acidocaldarius is a paracrystalline S-layer, and FlaF specifically bound to S-layer protein, suggesting that its interaction domain is located in the pseudoperiplasm with its N-terminal helix in the membrane. From these data, FlaF may act as the previously unknown archaellum stator protein that anchors the rotating archaellum to the archaeal cell envelope.
PDB ID: 4ZBHDownload
MMDB ID: 128949
PDB Deposition Date: 2015/4/14
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 1.5  Å
Source Organism:
Similar Structures:
Biological Unit for 4ZBH: dimeric; determined by author and by software (PISA)
Molecular Components in 4ZBH
Label Count Molecule
Proteins (2 molecules)
2
Conserved Flagellar Protein F
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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