ATP gamma S competes with ATP for binding at Domain 1 but not Domain 2 during ClpA catalyzed polypeptide translocation

作者：Miller Justin M; Lucius Aaron L^*

来源：Biophysical Chemistry, 2014, 185: 58-69.

DOI：10.1016/j.bpc.2013.11.002

• ATP dependent proteases
• AAA plus motor proteins
• Pre-steady-state kinetics
• Protein unfoldases
• Steady-state kinetics

ClpAP is an ATP-dependent protease that assembles through the association of hexameric rings of ClpA with the cylindrically-shaped protease ClpP. ClpA contains two nucleotide binding domains, termed Domain 1 (D1) or 2 (D2). We have proposed that D1 or D2 limits the rate of ClpA catalyzed polypeptide translocation when ClpP is either absent or present, respectively. Here we show that the rate of ClpA catalyzed polypeptide translocation depends on [ATP gamma S] in the absence of ClpP, but not in the presence of ClpP. We observe that ATP gamma S noncooperatively binds to ClpA during polypeptide translocation with an apparent affinity of similar to 6 mu M, but that introduction of ClpP shifts this affinity such that translocation is not affected. Interpreting these data with our proposed model for translocation catalyzed by ClpA vs. ClpAP suggests that ATP gamma S competes for binding at D1 but not at D2.

• 出版日期2014-1