Research Article The Role of Metals in the Reaction Catalyzed by Metal-Ion-Independent Bacillary RNase Yulia Sokurenko, 1 Vera Ulyanova, 1 Pavel Zelenikhin, 1 Alexey Kolpakov, 1 Dmitriy Blokhin, 2 Dieter Müller, 3 Vladimir Klochkov, 2 and Olga Ilinskaya 1 1 Institute of Fundamental Medicine and Biology, Kazan Federal University, Kremlevskaya Str. 18, Kazan 420008, Russia 2 Institute of Physics, Kazan Federal University, Kremlevskaya Str. 16a, Kazan 420008, Russia 3 Institute for Anatomy and Cell Biology, Justus Liebig University Giessen, Aulweg 123, 35385 Giessen, Germany Correspondence should be addressed to Yulia Sokurenko; sokurenko.yulia@gmail.com Received 25 August 2016; Revised 27 October 2016; Accepted 2 November 2016 Academic Editor: Spyros P. Perlepes Copyright © 2016 Yulia Sokurenko et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Extracellular enzymes of intestinal microbiota are the key agents that afect functional activity of the body as they directly interact with epithelial and immune cells. Several species of the Bacillus genus, like Bacillus pumilus, a common producer of extracellular RNase binase, can populate the intestinal microbiome as a colonizing organism. Without involving metal ions as cofactors, binase depolymerizes RNA by cleaving the 3  ,5  -phosphodiester bond and generates 2  ,3  -cyclic guanosine phosphates in the frst stage of a catalytic reaction. Maintained in the reaction mixture for more than one hour, such messengers can afect the human intestinal microfora and the human body. In the present study, we found that the rate of 2  ,3  -cGMP was growing in the presence of transition metals that stabilized the RNA structure. At the same time, transition metal ions only marginally reduced the amount of 2  ,3  -cGMP, blocking binase recognition sites of guanine at N7 of nucleophilic purine bases. 1. Introduction Te T1 family (EC 3.1.27.3) ribonucleases (RNases) hydrolize RNA and cleave the 3  ,5  -phosphodiester bond between guanosine 3  -phosphate and the 5  -OH group of the adjacent nucleotide, forming a 2  ,3  -cyclic guanosine phosphate in the frst stage of a catalytic reaction. Tis stage is reversible and is much faster than the second, in which the cyclic intermediate is hydrolyzed to a corresponding 3  -phosphate [1]. Unlike pyrimidine specifc RNases that belong to the family of RNase A (EC 3.1.27.5), RNases T1 are guanyl specifc; hence, 2  ,3  - cyclic guanosine monophosphate (2  ,3  -cGMP) can only be cleaved in the second step of catalysis [1]. Many members of genus Bacillus secrete RNases that can perform both stages of the catalytic reaction. Specifcally, such species are B. pumilus and B. licheniformis that can be isolated from the human gas- trointestinal tract, representing resident rather than transient microbiota [2]. Te amount of such microorganisms in the gastrointestinal tract signifcantly exceeds that which can be expected to come from food. Germination of Bacillus spores in the human intestine and transient colonization are part of the life cycle of human related bacilli [3]. Earlier, we have found B. pumilus in the biopsies of human rectal epithelium afer preoperative bowel cleansing [4]. Hence, products that are secreted by bacilli can afect the human normal fora and mediate changes in functional activity of the human body. Extracellular bacterial enzymes are key agents in relation to the human body, as they directly interact with epithelial and immune cells [5]. However, it would be erroneous to exclude from this interaction the reaction intermediates, such as 2  ,3  -cyclic positional isomers of classic second messen- gers, namely 3  ,5  -cAMP and 3  ,5  -cGMP. For instance, it is shown that 2  ,3  -cyclic nucleotides are involved in the regulation of mitochondrial permeability [6, 7]. In addition, 2  ,3  -cGMP can promote thymidine incorporation in the DNA of lymphocytes [8] and, similar to 3  ,5  -cGMP, can increase severalfold cGMP-dependent ATPase [9]. Although the biological role of 2  ,3  -cGMP has not yet been studied in Hindawi Publishing Corporation Bioinorganic Chemistry and Applications Volume 2016, Article ID 4121960, 7 pages http://dx.doi.org/10.1155/2016/4121960