Ribonucleoside Hydrolases–Structure, Functions, Physiological Role and Practical Uses

Abstract

Ribonucleoside hydrolases are enzymes that catalyze the cleavage of ribonucleosides to nitrogenous bases and ribose. These enzymes are found in many organisms: bacteria, archaea, protozoa, metazoans, yeasts, fungi and plants. Despite the simple reaction catalyzed by these enzymes, their physiological role in most organisms remains unclear. In this review, we compare the structure, kinetic parameters, physiological role, and potential applications of different types of ribonucleoside hydrolases discovered and isolated from different organisms.

Structure–Functional Examination of Novel Ribonucleoside Hydrolase C (RihC) from Limosilactobacillus reuteri LR1

“…In CfaRihC residues H82, Y229 and H241 are the only residues that coordinate the nitrogenous base of the substrate [ 5 , 10 ]. In the case of LreRihC, H237 (H241 in CfaRihC) has a similar orientation ( Figure 7 A,C); however, H86 and Y226 (H82 and Y229 in CfaRihC) are located on flexible regions 3 and 2, respectively ( Figure 5 E–G), and thus are far away from the active site, similar to the apo CfaRihC structure.…”

“…While this may be interesting in regards of conformation changes in RihC for catalysis, it may not explain the difference in catalytic properties (back in Table 2), while the differences in Region 2 (upper oval in Figure 8C) may do so. In CfaRihC residues H82, Y229 and H241 are the only residues that coordinate the nitrogenous base of the substrate [5,10]. In the case of LreRihC, H237 (H241 in CfaRihC) has a similar orientation (Figure 7A,C); however, H86 and Y226 (H82 and Y229 in Cfa-RihC) are located on flexible regions 3 and 2, respectively (Figure 5E-G), and thus are far away from active site, similar to the apo CfaRihC structure.…”

“…This enzyme belongs to the family of ribonucleoside hydrolases Rih, which includes several enzymes: IG–NH (inosine–guanosine-preferring nucleoside hydrolase), IAG–NH (inosine–adenosine–guanosine-preferring nucleoside hydrolase), RihA, RihB and RihC [ 5 ]. IG–NH and IAG–NH are purine-specific hydrolases, RihA and RihB are pyrimidine-specific hydrolases (also called CU–NH or cytidine–uridine-preferring nucleoside hydrolase), while RihC catalyzes reactions with both pyrimidines and purines [ 5 , 6 , 7 ]. The physiological role of this enzyme in lactobacilli and why it is synthesized specifically in response to the presence of pathogens is not completely clear.…”

“…RihC catalyzes the cleavage of ribonucleosides to nitrogenous bases and ribose. This enzyme belongs to the family of ribonucleoside hydrolases Rih, which includes several enzymes: IG-NH (inosine-guanosine-preferring nucleoside hydrolase), IAG-NH (inosine-adenosine-guanosine-preferring nucleoside hydrolase), RihA, RihB and RihC [5]. IG-NH and IAG-NH are purine-specific hydrolases, RihA and RihB are pyrimidine-specific hydrolases (also called CU-NH or cytidine-uridine-preferring nucleoside hydrolase), while RihC catalyzes reactions with both pyrimidines and purines [5][6][7].…”

Pyrimidine Biosynthesis and Ribonucleoside Metabolism in Species of Pseudomonas

“…It has been determined that a number of pyrimidine salvage enzymes can be involved in pyrimidine ribonucleoside metabolism in species of Pseudomonas and taxonomically related species [117][118][119]. In Figure 2, the relationship between pyrimidine ribonucleoside metabolism and subsequent pyrimidine base catabolism is shown.…”