Department of Biology, Faculty of Natural Sciences, University of Ss. Cyril and Methodius in Trnava, Námestie J. Herdu 577/2, 917 01, Trnava, Slovakia.
Department of Biology and Ecology, Faculty of Natural Sciences, Matej Bel University, 974 01, Banská Bystrica, Slovakia.
Sci Rep. 2022 Aug 16;12(1):13872. doi: 10.1038/s41598-022-18228-2.
Calpains are cysteine proteases involved in many cellular processes. They are an ancient and large superfamily of enzymes responsible for the cleavage and irreversible modification of a large variety of substrates. They have been intensively studied in humans and other mammals, but information about calpains in bacteria is scarce. Calpains have not been found among Archaea to date. In this study, we have investigated the presence of calpains in selected cyanobacterial species using in silico analyses. We show that calpains defined by possessing CysPC core domain are present in cyanobacterial genera Anabaena, Aphanizomenon, Calothrix, Chamaesiphon, Fischerella, Microcystis, Scytonema and Trichormus. Based on in silico protein interaction analysis, we have predicted putative interaction partners for identified cyanobacterial calpains. The phylogenetic analysis including cyanobacterial, other bacterial and eukaryotic calpains divided bacterial and eukaryotic calpains into two separate monophyletic clusters. We propose two possible evolutionary scenarios to explain this tree topology: (1) the eukaryotic ancestor or an archaeal ancestor of eukaryotes obtained calpain gene from an unknown bacterial donor, or alternatively (2) calpain gene had been already present in the last common universal ancestor and subsequently lost by the ancestor of Archaea, but retained by the ancestor of Bacteria and by the ancestor of Eukarya. Both scenarios would require multiple independent losses of calpain genes in various bacteria and eukaryotes.
钙蛋白酶是参与多种细胞过程的半胱氨酸蛋白酶。它们是一个古老而庞大的酶超家族，负责切割和不可逆修饰多种底物。它们在人类和其他哺乳动物中得到了深入研究，但关于细菌中的钙蛋白酶的信息却很少。迄今为止，在古菌中尚未发现钙蛋白酶。在这项研究中，我们使用计算机分析方法研究了选定蓝藻物种中钙蛋白酶的存在情况。我们表明，具有 CysPC 核心结构域的钙蛋白酶存在于蓝藻属 Anabaena、Aphanizomenon、Calothrix、Chamaesiphon、Fischerella、Microcystis、Scytonema 和 Trichormus 中。基于计算机蛋白质相互作用分析，我们预测了鉴定出的蓝藻钙蛋白酶的潜在相互作用伙伴。包括蓝藻、其他细菌和真核生物钙蛋白酶的系统发育分析将细菌和真核生物钙蛋白酶分为两个独立的单系群。我们提出了两种可能的进化情景来解释这种树拓扑结构：（1）真核生物的祖先或真核生物的古菌祖先从未知的细菌供体中获得了钙蛋白酶基因，或者（2）钙蛋白酶基因已经存在于最后一个共同的原始生物中，并随后被古菌的祖先丢失，但被细菌的祖先和真核生物的祖先保留。这两种情景都需要在各种细菌和真核生物中多次独立丢失钙蛋白酶基因。
