Further insight into the inhibitory action of a LIM/double zinc-finger motif of an agmatinase-like protein.

Further insight into the inhibitory action of a LIM/double zinc-finger motif of an agmatinase-like protein. J Inorg Biochem. 2013 Dec 25; Authors: Cofre J, Montes P, Vallejos A, Benítez J, García D, Martínez-Oyanedel J, Carvajal N, Uribe E Abstract Agmatine is a precursor for polyamine biosynthesis also associated to neurotransmitter, anticonvulsant, antineurotoxic and antidepressant actions in the brain. It results from decarboxylation of l-arginine by arginine decarboxylase and it is hydrolyzed to urea and putrescine by agmatinase. Recently, we have described a new protein which also hydrolyzes agmatine although its sequence greatly differs from all known agmatinases. This agmatinase-like protein (ALP) contains a LIM-like double Zn-finger domain close to its carboxyl terminus, whose removal results in a truncated variant with a 10-fold increased kcat, and a 3-fold decreased Km value for agmatine. Our proposal was that the LIM-domain functions as an autoinhibitory, regulatory entity for ALP. Results in this report provide additional support for the postulated inhibitory effect. The purified isolated LIM domain was shown to be competitively inhibitory to a truncated variant ALP (lacking the LIM-domain), but not to the wild-type species. The C453A variant was shown to be a Zn(2+)-free enzyme with kinetic parameters similar to those of the truncated-ALP. A molecular dynamic simulation of a modeled LIM-domain 3D structure showed that, as a con...
Source: Journal of Inorganic Biochemistry - Category: Biochemistry Authors: Tags: J Inorg Biochem Source Type: research