4I84

The crystal structure of the Haemophilus influenzae HxuA secretion domain involved in the two-partner secretion pathway

Summary for 4I84

• Entry DOI: 10.2210/pdb4i84/pdb
• Descriptor: Heme/hemopexin-binding protein (2 entities in total)
• Functional Keywords: beta-helix, two-partner secretion pathway, hxub, protein transport
• Biological source: Haemophilus influenzae
• Cellular location: Secreted: P44602
• Total number of polymer chains: 2
• Total formula weight: 65935.39

Authors

Baelen, S.,Dewitte, F.,Clantin, B.,Villeret, V. (deposition date: 2012-12-03, release date: 2013-11-13, Last modification date: 2023-09-20)

Primary citation

Baelen, S.,Dewitte, F.,Clantin, B.,Villeret, V.
Structure of the secretion domain of HxuA from Haemophilus influenzae.
Acta Crystallogr.,Sect.F, 69:1322-1327, 2013

PubMed Abstract: Haemophilus influenzae HxuA is a cell-surface protein with haem-haemopexin binding activity which is key to haem acquisition from haemopexin and thus is one of the potential sources of haem for this microorganism. HxuA is secreted by its specific transporter HxuB. HxuA/HxuB belongs to the so-called two-partner secretion systems (TPSs) that are characterized by a conserved N-terminal domain in the secreted protein which is essential for secretion. Here, the 1.5 Å resolution structure of the secretion domain of HxuA, HxuA301, is reported. The structure reveals that HxuA301 folds into a β-helix domain with two extra-helical motifs, a four-stranded β-sheet and an N-terminal cap. Comparisons with other structures of TpsA secretion domains are reported. They reveal that despite limited sequence identity, strong structural similarities are found between the β-helix motifs, consistent with the idea that the TPS domain plays a role not only in the interaction with the specific TpsB partners but also as the scaffold initiating progressive folding of the TpsA proteins at the bacterial surface.

PubMed: 24316822
DOI: 10.1107/S174430911302962X

Experimental method

X-RAY DIFFRACTION (1.5 Å)