期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 278, 期 36, 页码 34172-34180出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M303689200
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资金
- NCRR NIH HHS [RR07707] Funding Source: Medline
- NHLBI NIH HHS [HL66219] Funding Source: Medline
- NIAMS NIH HHS [P01 AR041637, AR41637] Funding Source: Medline
A nucleotide-dependent conformational change regulates actin filament dynamics. Yet, the structural basis of this mechanism remains controversial. The x-ray crystal structure of tetramethylrhodamine-5-maleimide-actin with bound AMPPNP, a non-hydrolyzable ATP analog, was determined to 1.85-Angstrom resolution. A comparison of this structure to that of tetramethylrhodamine-5- maleimide-actin with bound ADP, determined previously under similar conditions, reveals how the release of the nucleotide gamma-phosphate sets in motion a sequence of events leading to a conformational change in subdomain 2. The side chain of Ser-14 in the catalytic site rotates upon Pi release, triggering the rearrangement of the loop containing the methylated His-73, referred to as the sensor loop. This in turn causes a transition in the DNase I-binding loop in subdomain 2 from a disordered loop in ATP-actin to an ordered alpha-helix in ADP-actin. Despite this conformational change, the nucleotide cleft remains closed in ADP-actin, similar to ATP-actin. An analysis of the existing structures of members of the actin superfamily suggests that the cleft is open in the nucleotide-free state.
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