An evolutionally conserved Lys122 is essential for function in Rhodospirillum rubrum bona fide RuBisCO and Bacillus subtilis RuBisCO-like protein

作者：Nakano Toshihiro; Ashida Hiroki^*; Mizohata Eiichi; Matsumura Hiroyoshi; Yokota Akiho

来源：Biochemical and Biophysical Research Communications, 2010, 392(2): 212-216.

DOI：10.1016/j.bbrc.2010.01.017

• RuBisCO
• RuBisCO-like protein
• RuBisCO superfamily
• Rhodospirillum rubrum
• Bacillus subtilis

Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and RuBisCO-like protein (RLP) catalyze similar enolase-type reactions. Both enzymes have a conserved non-catalytic Lys122 or Arg122 on the beta-strand E lying in the interface between the N- and C-terminal domains. We used site-directed mutagenesis to analyze the function of Lys122 in the form II Rhodospirillum rubrum RuBisCO (RrRuBisCO) and Bacillus subtilis RLP (BsRLP). The K122R mutant of RrRuBisCO had a 40% decrease in k(eat) for carboxylase activity, a 2-fold increase in K-m for CO2, and a 1.9-fold increase in K-m for ribulose-1,5-bisphosphate. K122M and K122E mutants of RrRuBisCO were almost inactive. None of the substitutions affected the thermal stability of RrRuBisCO. The K122R mutant of BsRLP had a 32% decrease in k(cat) and lower thermal stability than the wild-type enzyme. The K122M and K122E mutants of BsRLP failed to form a catalytic dimer. Our results suggest that the lysine residue is essential for function in both enzymes, although in each case, its role is likely distinct.

• 出版日期2010-2-5