Department of Chemistry, Division of Biochemistry, University of Natural Resources and Life Sciences (BOKU), A-1190, Vienna, Austria.
Institute of Molecular Biology, Slovak Academy of Sciences, SK-84551, Bratislava, Slovakia.
Sci Rep. 2017 Aug 24;7(1):9393. doi: 10.1038/s41598-017-09581-8.
Heme peroxidases, essential peroxide converting oxidoreductases are divided into four independently evolved superfamilies. Within the largest one - the peroxidase-catalase superfamily - two hybrid lineages were described recently. Whereas Hybrid A heme peroxidases represent intermediate enzymes between ascorbate peroxidases and cytochrome c peroxidases, Hybrid B heme peroxidases are unique fusion proteins comprised of a conserved N-terminal heme peroxidase domain and a C-terminal domain of various sugar binding motifs. So far these peculiar peroxidases are only found in the kingdom of Fungi. Here we present a phylogenetic reconstruction of the whole superfamily with focus on Hybrid B peroxidases. We analyse the domain assembly and putative structure and function of the newly discovered oligosaccharide binding domains. Two distinct carbohydrate binding modules (CBM21 and CBM34) are shown to occur in phytopathogenic ascomycetous orthologs of Hybrid B heme peroxidases only. Based on multiple sequence alignment and homology modeling the structure-function relationships are discussed with respect to physiological function. A concerted action of peroxide cleavage with specific cell-wall carbohydrate binding can support phytopathogens survival within the plant host.
血红素过氧化物酶，作为必需的过氧化物转化氧化还原酶，可分为四个独立进化的超家族。在最大的一个超家族——过氧化物酶-过氧化氢酶超家族中，最近描述了两个杂交谱系。而杂交 A 血红素过氧化物酶是抗坏血酸过氧化物酶和细胞色素 c 过氧化物酶之间的中间酶，杂交 B 血红素过氧化物酶则是由保守的 N 端血红素过氧化物酶结构域和 C 端各种糖结合基序的结构域组成的独特融合蛋白。到目前为止，这些特殊的过氧化物酶仅在真菌界中发现。在这里，我们对整个超家族进行了系统发育重建，重点是杂交 B 过氧化物酶。我们分析了新发现的寡糖结合结构域的结构组装和潜在的结构和功能。研究表明，只有在植物病原性子囊菌的杂交 B 血红素过氧化物酶的同源物中才存在两种不同的碳水化合物结合模块（CBM21 和 CBM34）。基于多重序列比对和同源建模，我们讨论了结构-功能关系及其与生理功能的关系。过氧化物分解与特定细胞壁碳水化合物结合的协同作用可以支持植物病原菌在植物宿主内的生存。
