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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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Modular architecture of Hia and putative two-step adhesive mechanism. (a) Modular architecture of Hia adhesin. While the structures of IN1, W1, KG1, W3, IN2, W5, Neck, and transmembrane anchor/translocator domains are determined crystallographically, W2/W4 and KG2 are modeled based on W1/W3/W5 and KG1, respectively. Yellow rectangles represent the Hia sequences that are yet to be structurally characterized, including the predicted N-terminal GANG and C-terminal TTT domains. (b) A putative two-step adhesive mechanism utilized by Hia/Hsf-like adhesin to form an intimate association between the bacterium and the host cell. The adhesive Trp-ring domains with different binding capacities are shown in blue and red. The nonadhesive Trp-ring domains are shown in green.
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fig6: Modular architecture of Hia and putative two-step adhesive mechanism. (a) Modular architecture of Hia adhesin. While the structures of IN1, W1, KG1, W3, IN2, W5, Neck, and transmembrane anchor/translocator domains are determined crystallographically, W2/W4 and KG2 are modeled based on W1/W3/W5 and KG1, respectively. Yellow rectangles represent the Hia sequences that are yet to be structurally characterized, including the predicted N-terminal GANG and C-terminal TTT domains. (b) A putative two-step adhesive mechanism utilized by Hia/Hsf-like adhesin to form an intimate association between the bacterium and the host cell. The adhesive Trp-ring domains with different binding capacities are shown in blue and red. The nonadhesive Trp-ring domains are shown in green.

Mentions: In this study, we identified novel distinguishing features of Hia. In particular, the Hia passenger domain consists of repeats of structurally similar domains, including five structurally identical Trp-ring domains strung together by two IsNeck domains and two KG domains (Fig. 6). Furthermore, we found that the IsNeck domains and the KG domains share a similar three-dimensional organization, although they differ topologically. At the C-terminus, the multidomain structure of the passenger domain is connected to the Hia membrane anchor/translocator domain via an α-helical coiled-coil-like structure preceded by a Neck connector domain.


Repetitive architecture of the Haemophilus influenzae Hia trimeric autotransporter.

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

Modular architecture of Hia and putative two-step adhesive mechanism. (a) Modular architecture of Hia adhesin. While the structures of IN1, W1, KG1, W3, IN2, W5, Neck, and transmembrane anchor/translocator domains are determined crystallographically, W2/W4 and KG2 are modeled based on W1/W3/W5 and KG1, respectively. Yellow rectangles represent the Hia sequences that are yet to be structurally characterized, including the predicted N-terminal GANG and C-terminal TTT domains. (b) A putative two-step adhesive mechanism utilized by Hia/Hsf-like adhesin to form an intimate association between the bacterium and the host cell. The adhesive Trp-ring domains with different binding capacities are shown in blue and red. The nonadhesive Trp-ring domains are shown in green.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2597055&req=5

fig6: Modular architecture of Hia and putative two-step adhesive mechanism. (a) Modular architecture of Hia adhesin. While the structures of IN1, W1, KG1, W3, IN2, W5, Neck, and transmembrane anchor/translocator domains are determined crystallographically, W2/W4 and KG2 are modeled based on W1/W3/W5 and KG1, respectively. Yellow rectangles represent the Hia sequences that are yet to be structurally characterized, including the predicted N-terminal GANG and C-terminal TTT domains. (b) A putative two-step adhesive mechanism utilized by Hia/Hsf-like adhesin to form an intimate association between the bacterium and the host cell. The adhesive Trp-ring domains with different binding capacities are shown in blue and red. The nonadhesive Trp-ring domains are shown in green.
Mentions: In this study, we identified novel distinguishing features of Hia. In particular, the Hia passenger domain consists of repeats of structurally similar domains, including five structurally identical Trp-ring domains strung together by two IsNeck domains and two KG domains (Fig. 6). Furthermore, we found that the IsNeck domains and the KG domains share a similar three-dimensional organization, although they differ topologically. At the C-terminus, the multidomain structure of the passenger domain is connected to the Hia membrane anchor/translocator domain via an α-helical coiled-coil-like structure preceded by a Neck connector domain.

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