The study presents an in silico identification of poly (cis-1,4-isoprene) cleaving enzymes, viz., RoxA and RoxB in bacteria, followed by their functional and evolutionary exploration using comparative genomics. The orthologs of these proteins were found to be restricted to Gram-negative beta-, gamma-, and delta-proteobacteria. Toward the evolutionary propagation, the RoxA and RoxB genes were predicted to have evolved via a common interclass route of horizontal gene transfer in the phylum Proteobacteria (delta → gamma → beta). Besides, recombination, mutation, and gene conversion were also detected in both the genes leading to their diversification. Further, the differential selective pressure is predicted to be operating on entire RoxA and RoxB genes such that the former is diversifying further, whereas the latter is evolving to reduce its genetic diversity. However, the structurally and functionally important sites/residues of these genes were found to be preventing changes implying their evolutionary conservation. Further, the phylogenetic analysis demonstrated a sharp split between the RoxA and RoxB orthologs and indicated the emergence of their variant as another type of putative rubber oxygenase (RoxC) in the class Gammaproteobacteria. A detailed in silico analysis of the signature motifs and residues of Rox sequences exhibited important differences as well as similarities among the RoxA, RoxB, and putative RoxC sequences. Although RoxC appears to be a hybrid of RoxA and RoxB, the signature motifs and residues of RoxC are more similar to RoxB.

该研究提出了细菌中聚（顺式-1,4-异戊二烯）裂解酶（即 RoxA 和 RoxB）的计算机鉴定，然后使用比较基因组学对其功能和进化进行探索。发现这些蛋白质的直系同源物仅限于革兰氏阴性β-、γ-和δ-变形菌。对于进化传播， RoxA和RoxB基因被预测是通过变形菌门水平基因转移的共同类间途径进化的（δ → gamma → beta）。此外，在这两个基因中也检测到了重组、突变和基因转换，导致了它们的多样化。此外，预计差异选择压力将作用于整个RoxA和RoxB基因，使得前者进一步多样化，而后者正在进化以减少其遗传多样性。然而，这些基因的结构和功能上重要的位点/残基被发现阻止了意味着它们的进化保守性的变化。此外，系统发育分析表明 RoxA 和 RoxB 直向同源物之间存在明显分裂，并表明它们的变体作为 Gammaproteobacteria 类中另一种推定的橡胶加氧酶 (RoxC) 的出现。对 Rox 序列的特征基序和残基的详细计算机分析显示了 RoxA、RoxB 和假定的 RoxC 序列之间的重要差异和相似性。尽管 RoxC 似乎是 RoxA 和 RoxB 的杂合体，但 RoxC 的特征基序和残基与 RoxB 更相似。