Preliminary crystallographic study of the molybdenum cofactor biosynthesis protein MocA complexed with CTP from Mycobacterium sp. strain JC1 DSM 3803

Abstract

In the biosynthesis of molybdopterin cytosine dinucleotide cofactor, MocA, molybdenum cofactor cytidylyltransferase, transfers the cytosine monophosphate moiety from cytosine triphosphate (CTP) to Mo-molybdopterin. In this study, we heterologously overexpressed MocA from Mycobacterium sp. strain JC1 DSM 3803 and purified the protein by Ni-NTA affinity and size-exclusion chromatography. The MocA protein was incubated with CTP and MnCl 2 , then crystallized under conditions containing 10% polyethylene glycol 6000 and 2 M sodium chloride. X-ray diffraction data were acquired at 1.55 Å resolution and belonged to the space group a P4 3 2 1 2, with unit cell parameters a = 53.965 Å, b = 53.965 Å, c = 130.184 Å, and α = β = γ = 90°. An asymmetric unit of the crystal contains one MocA molecule with solvent content of 45.49% and Mathewes coefficient of 2.26 Å 3 /Da. A high-quality electron density map for the MocA complexed with CTP was obtained by a molecular replacement method.