Hansberg Wilhelm, Nava-Ramírez Teresa, Rangel-Silva Pablo, Díaz-Vilchis Adelaida, Mendoza-Oliva Aydé
Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, UNAM, Mexico City 04510, Mexico.
Center for Alzheimer's and Neurodegenerative Diseases, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
Antioxidants (Basel). 2022 May 17;11(5):979. doi: 10.3390/antiox11050979.
Bacterial and fungal large-size subunit catalases (LSCs) are like small-size subunit catalases (SSCs) but have an additional C-terminal domain (CT). The catalytic domain is conserved at both primary sequence and structural levels and its amino acid composition is optimized to select HO over water. The CT is structurally conserved, has an amino acid composition similar to very stable proteins, confers high stability to LSCs, and has independent molecular chaperone activity. While heat and denaturing agents increased catalase-1 (CAT-1) activity, a CAT-1 version lacking the CT (C63) was no longer activated by these agents. The addition of catalase-3 (CAT-3) CT to the CAT-1 or CAT-3 catalase domains prevented their heat denaturation in vitro. Protein structural alignments indicated CT similarity with members of the DJ-1/PfpI superfamily and the CT dimers present in LSCs constitute a new type of symmetric dimer within this superfamily. However, only the bacterial Hsp31 proteins show sequence similarity to the bacterial and fungal catalase mobile coil (MC) and are phylogenetically related to MC_CT sequences. LSCs might have originated by fusion of SSC and Hsp31 encoding genes during early bacterial diversification, conferring at the same time great stability and molecular chaperone activity to the novel catalases.
细菌和真菌的大尺寸亚基过氧化氢酶（LSCs）与小尺寸亚基过氧化氢酶（SSCs）相似，但有一个额外的C末端结构域（CT）。催化结构域在一级序列和结构水平上都是保守的，其氨基酸组成经过优化，以选择过氧化氢而非水。CT在结构上是保守的，其氨基酸组成与非常稳定的蛋白质相似，赋予LSCs高稳定性，并具有独立的分子伴侣活性。虽然热和变性剂增加了过氧化氢酶-1（CAT-1）的活性，但缺乏CT的CAT-1版本（C63）不再被这些试剂激活。将过氧化氢酶-3（CAT-3）的CT添加到CAT-1或CAT-3过氧化氢酶结构域可防止它们在体外热变性。蛋白质结构比对表明CT与DJ-1/PfpI超家族成员相似，LSCs中存在的CT二聚体构成了该超家族内一种新型的对称二聚体。然而，只有细菌Hsp31蛋白与细菌和真菌过氧化氢酶的移动线圈（MC）具有序列相似性，并且在系统发育上与MC_CT序列相关。LSCs可能起源于早期细菌分化过程中SSC和Hsp31编码基因的融合，同时赋予新型过氧化氢酶极大的稳定性和分子伴侣活性。
