The arginine finger of the Bloom syndrome protein: its structural organization and its role in energy coupling.
RecQ family helicases are essential in maintaining chromosomal DNA stability and integrity. Despite extensive studies, the mechanisms of these enzymes are still poorly understood. Crystal structures of many helicases reveal a highly conserved arginine residue located near the gamma-phosphate of ATP. This residue is widely recognized as an arginine finger, and may sense ATP binding and hydrolysis, and transmit conformational changes. We investigated the existence and role of the arginine finger in the Bloom syndrome protein (BLM), a RecQ family helicase, in ATP hydrolysis and energy coupling. Our studies by combination of structural modelling, site-directed mutagenesis and biochemical and biophysical approaches, demonstrate that mutations of residues interacting with the gamma-phosphate of ATP or surrounding the ATP-binding sites result in severe impairment in the ATPase activity of BLM. These mutations also impair BLM's DNA-unwinding activities, but do not affect its ATP and DNA-binding abilities. These data allow us to identify R982 as the residue that functions as a BLM arginine finger. Our findings further indicate how the arginine finger is precisely positioned by the conserved motifs with respect to the gamma-phosphate.
Ren
Hua
H
School of Life Science, East China Normal University, Science Bld., 3663 North Zhongshan Rd., Shanghai 200062, PR China.
Dou
Shuo-Xing
SX
Rigolet
Pascal
P
Yang
Ye
Y
Wang
Peng-Ye
PY
Amor-Gueret
Mounira
M
Xi
Xu Guang
XG
D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry*; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D053484:RecQ Helicases; D014638:Vanadates / Q000494:pharmacology
D014638:Vanadates; D000255:Adenosine Triphosphate; D004247:DNA; D001120:Arginine; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D004265:DNA Helicases; D053484:RecQ Helicases