Recognition of different nucleotidyl-derivatives as substrates of reactions catalyzed by various HIT-proteinsThis article is part of a themed issue on Biophosphates.This paper is dedicated to Professor Wojciech J. Stec on the occasion of his 70th birthday.

Proteins that have a histidine triad in their active sites belong to the HIT-protein superfamily. They are ubiquitous, are involved in the metabolism of different nucleotides and catalyze their hydrolysis and/or phosphorolysis liberating either the corresponding 5′-NMP or 5′-NDP, respectively. We studied substrate specificity of nine recombinant HIT-proteins with adenosine 5′-phosphosulfate (1), adenosine 5′-phosphoramidate (2), adenosine 5′-phosphorothioate (3), adenosine 5′-phosphorofluoride (4), diadenosine 5′,5′′′-P1,P3-triphosphate (5), di(7-methylguanosine) 5′,5′′′-P1,P3-triphosphate (6) and adenosine 5′-hypophosphate (7). Preferences for the recognition of these compounds as substrates by individual proteins differed. All the proteins hydrolyzed (1) but the Arabidopsis thalianaHint1 did it very slowly. None of the proteins cleaved (7). Only A. thalianaHint1 and Escherichia coliHinT hydrolyzed (3). Three proteins known as dinucleoside triphosphatases, human and A. thalianaFhit-proteins and Trypanosoma bruceiHIT-45, cleaved (1), (2), (4), (5) and (6). Caenorhabditis elegansdecapping protein DcpS degraded (1), (5), (6) and poorly (4). A. thalianaaprataxin-like protein and Hint4 hydrolyzed only (1), (2) and (4), in that order of efficiency. Velocities of those reactions and some Kmvalues were determined. Applicability of this study to the metabolism of certain nucleotidyl-derivatives is discussed. [ABSTRACT FROM AUTHOR]