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Repetitive architecture of the Haemophilus influenzae Hia trimeric autotransporter.

Meng G, St Geme JW, Waksman G - J. Mol. Biol. (2008)

Bottom Line: Comparison of the structures of HiaBD1 and HiaBD2 adhesive repeats and a nonadhesive repeat (a novel fold) shed light on the structural determinants of Hia adhesive function.Examination of the structure of an extended version of the Hia translocator domain revealed the structural transition between the C-terminal translocator domain and the N-terminal passenger domain, highlighting a highly intertwined domain that is ubiquitous among trimeric autotransporters.Overall, this study provides important insights into the mechanism of Hia adhesive activity and the overall structure of trimeric autotransporters.

View Article: PubMed Central - PubMed

Affiliation: Institute of Structural and Molecular Biology at UCL/Birkbeck, London, UK.

ABSTRACT
The Hia autotransporter of Haemophilus influenzae belongs to the trimeric autotransporter subfamily and mediates bacterial adherence to the respiratory epithelium. In this report, we show that the structure of Hia is characterized by a modular architecture containing repeats of structurally distinct domains. Comparison of the structures of HiaBD1 and HiaBD2 adhesive repeats and a nonadhesive repeat (a novel fold) shed light on the structural determinants of Hia adhesive function. Examination of the structure of an extended version of the Hia translocator domain revealed the structural transition between the C-terminal translocator domain and the N-terminal passenger domain, highlighting a highly intertwined domain that is ubiquitous among trimeric autotransporters. Overall, this study provides important insights into the mechanism of Hia adhesive activity and the overall structure of trimeric autotransporters.

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Structure comparison between Trp-ring domains. (a) Stereo ribbon diagram of the superimposed W1 (blue), W3 (green), and W5 (red) domains viewed from the side. (b) Stereo ribbon diagram of the superimposed Trp-ring domains viewed from the top. (c) Sequence alignment of the Trp-ring domains between Hia/Hsf/NhhA. In (a) and (b), the conserved residues at the trimeric interface are shown in stick representation. In (c), these residues are shown in blue.
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fig4: Structure comparison between Trp-ring domains. (a) Stereo ribbon diagram of the superimposed W1 (blue), W3 (green), and W5 (red) domains viewed from the side. (b) Stereo ribbon diagram of the superimposed Trp-ring domains viewed from the top. (c) Sequence alignment of the Trp-ring domains between Hia/Hsf/NhhA. In (a) and (b), the conserved residues at the trimeric interface are shown in stick representation. In (c), these residues are shown in blue.

Mentions: Comparison of all of the available Trp-ring domain structures of Hia, namely, W1 (residues 117–166), W3 (residues 372–421), and W5 (residues 654–705), reveals only minor differences (Fig. 4). The RMSDs of the main-chain atoms of these Trp-ring domains are 1.6 Å between W1 and W3, 1.7 Å between W3 and W5, and 1.5 Å between W1 and W5. The major variations among these structures lie in the βW1–βW2, βW3–βW4, and βW4–βW5 loops away from the axial hydrophobic cavity of the trimer (Fig. 4). Overall, the most highly conserved residues map at the trimeric interface (Fig. 4b and c). Two invariant aromatic residues in the βW1 and βW3 strands of the W1, W3, and W5 Trp-ring domains (W118/W373/W655 and F142/F398/F681, respectively) are found in immediate trimeric contact in the upper part of the Trp-ring domain. Another two invariant Val residues in the βW2 and βW3 strands (V134/V390/V673 and V140/V396/V679) also map to this region and could play a supportive role underneath the invariant Trp residues (Fig. 4c). Finally, a third less conserved aromatic patch in the βW5 strand is clearly visible in the lower part of the W1, W3, and W5 domains (F163/Y419/F702) (Fig. 4). The only W domain in which this aromatic ring is not seen is W2, where the trimeric interface is mediated by Ile residues (Fig. 4c).


Repetitive architecture of the Haemophilus influenzae Hia trimeric autotransporter.

Meng G, St Geme JW, Waksman G - J. Mol. Biol. (2008)

Structure comparison between Trp-ring domains. (a) Stereo ribbon diagram of the superimposed W1 (blue), W3 (green), and W5 (red) domains viewed from the side. (b) Stereo ribbon diagram of the superimposed Trp-ring domains viewed from the top. (c) Sequence alignment of the Trp-ring domains between Hia/Hsf/NhhA. In (a) and (b), the conserved residues at the trimeric interface are shown in stick representation. In (c), these residues are shown in blue.
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Show All Figures
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fig4: Structure comparison between Trp-ring domains. (a) Stereo ribbon diagram of the superimposed W1 (blue), W3 (green), and W5 (red) domains viewed from the side. (b) Stereo ribbon diagram of the superimposed Trp-ring domains viewed from the top. (c) Sequence alignment of the Trp-ring domains between Hia/Hsf/NhhA. In (a) and (b), the conserved residues at the trimeric interface are shown in stick representation. In (c), these residues are shown in blue.
Mentions: Comparison of all of the available Trp-ring domain structures of Hia, namely, W1 (residues 117–166), W3 (residues 372–421), and W5 (residues 654–705), reveals only minor differences (Fig. 4). The RMSDs of the main-chain atoms of these Trp-ring domains are 1.6 Å between W1 and W3, 1.7 Å between W3 and W5, and 1.5 Å between W1 and W5. The major variations among these structures lie in the βW1–βW2, βW3–βW4, and βW4–βW5 loops away from the axial hydrophobic cavity of the trimer (Fig. 4). Overall, the most highly conserved residues map at the trimeric interface (Fig. 4b and c). Two invariant aromatic residues in the βW1 and βW3 strands of the W1, W3, and W5 Trp-ring domains (W118/W373/W655 and F142/F398/F681, respectively) are found in immediate trimeric contact in the upper part of the Trp-ring domain. Another two invariant Val residues in the βW2 and βW3 strands (V134/V390/V673 and V140/V396/V679) also map to this region and could play a supportive role underneath the invariant Trp residues (Fig. 4c). Finally, a third less conserved aromatic patch in the βW5 strand is clearly visible in the lower part of the W1, W3, and W5 domains (F163/Y419/F702) (Fig. 4). The only W domain in which this aromatic ring is not seen is W2, where the trimeric interface is mediated by Ile residues (Fig. 4c).

Bottom Line: Comparison of the structures of HiaBD1 and HiaBD2 adhesive repeats and a nonadhesive repeat (a novel fold) shed light on the structural determinants of Hia adhesive function.Examination of the structure of an extended version of the Hia translocator domain revealed the structural transition between the C-terminal translocator domain and the N-terminal passenger domain, highlighting a highly intertwined domain that is ubiquitous among trimeric autotransporters.Overall, this study provides important insights into the mechanism of Hia adhesive activity and the overall structure of trimeric autotransporters.

View Article: PubMed Central - PubMed

Affiliation: Institute of Structural and Molecular Biology at UCL/Birkbeck, London, UK.

ABSTRACT
The Hia autotransporter of Haemophilus influenzae belongs to the trimeric autotransporter subfamily and mediates bacterial adherence to the respiratory epithelium. In this report, we show that the structure of Hia is characterized by a modular architecture containing repeats of structurally distinct domains. Comparison of the structures of HiaBD1 and HiaBD2 adhesive repeats and a nonadhesive repeat (a novel fold) shed light on the structural determinants of Hia adhesive function. Examination of the structure of an extended version of the Hia translocator domain revealed the structural transition between the C-terminal translocator domain and the N-terminal passenger domain, highlighting a highly intertwined domain that is ubiquitous among trimeric autotransporters. Overall, this study provides important insights into the mechanism of Hia adhesive activity and the overall structure of trimeric autotransporters.

Show MeSH
Related in: MedlinePlus