Oxygen-Induced Conformational Changes in the PAS-Heme Domain of the Pseudomonas aeruginosa Aer2 Receptor.
Biochemistry
; 60(34): 2610-2622, 2021 08 31.
Article
en En
| MEDLINE
| ID: mdl-34383467
ABSTRACT
The Aer2 receptor from Pseudomonas aeruginosa has an O2-binding PAS-heme domain that stabilizes O2 via a Trp residue in the distal heme pocket. Trp rotates â¼90° to bond with the ligand and initiate signaling. Although the isolated PAS domain is monomeric, both in solution and in a cyanide-bound crystal structure, an unliganded structure forms a dimer. An overlay of the two structures suggests possible signaling motions but also predicts implausible clashes at the dimer interface when the ligand is bound. Moreover, in a full-length Aer2 dimer, PAS is sandwiched between multiple N- and C-terminal HAMP domains, which would feasibly restrict PAS motions. To explore the PAS dimer interface and signal-induced motions in full-length Aer2, we introduced Cys substitutions and used thiol-reactive probes to examine in vivo accessibility and residue proximities under both aerobic and anaerobic conditions. In vivo, PAS dimers were retained in full-length Aer2 in the presence and absence of O2, and the dimer interface was consistent with the isolated PAS dimer structure. O2-mediated changes were also consistent with structural predictions in which the PAS N-terminal caps move apart and the C-terminal DxT region moves closer together. The DxT motif links PAS to the C-terminal HAMP domains and was critical for PAS-HAMP signaling. Removing the N-terminal HAMP domains altered the distal PAS dimer interface and prevented signaling, even after signal-on lesions were introduced into PAS. The N-terminal HAMP domains thus facilitate the O2-dependent shift of PAS to the signal-on conformation, clarifying their role upstream of the PAS-sensing domain.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Oxígeno
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Pseudomonas aeruginosa
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Infecciones por Pseudomonas
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Proteínas Bacterianas
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Proteínas de Escherichia coli
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Sistemas de Secreción Tipo III
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Proteínas de Unión al Hemo
/
Hemo
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Biochemistry
Año:
2021
Tipo del documento:
Article
País de afiliación:
Estados Unidos