Crystal structure of phosphotransacetylase from the methanogenic archaeon Methanosarcina thermophila. Journal   Structure (Cambridge, Mass. : 2001) Citation   Structure (Camb). 12(4):559-67 Publication date   2004 Apr Authors   Iyer PP Lawrence SH Luther KB Rajashankar KR Yennawar HP Ferry JG Schindelin H Investigators   Gregory Ferry Grant agencies   National Institute of Diabetes and Digestive and Kidney Diseases National Institute of General Medical Sciences Grants   NIDDK DK54835 NIGMS GM44661 MeSH headings   Archaeal Proteins Methanosarcina Phosphate Acetyltransferase MeSH qualifiers   chemistry enzymology Abstract   Phosphotransacetylase (Pta) [EC 2.3.1.8] is ubiquitous in the carbon assimilation and energy-yielding pathways in anaerobic prokaryotes where it catalyzes the reversible transfer of the acetyl group from acetyl phosphate to CoA forming acetyl CoA and inorganic phosphate. The crystal structure of Pta from the methane-producing archaeon Methanosarcina thermophila, representing the first crystal structure of any Pta, was determined by multiwavelength anomalous diffraction at 2.7 A resolution. In solution and in the crystal, the enzyme forms a homodimer. Each monomer consists of two alpha/beta domains with a cleft along the domain boundary, which presumably contains the substrate binding sites. Comparison of the four monomers present in the asymmetric unit indicates substantial variations in the relative orientation of the two domains and the structure of the putative active site cleft. A search for structural homologs revealed the NADP(+)-dependent isocitrate and isopropylmalate dehydrogenases as the only homologs with a similar two-domain architecture.