title: A novel mechanism of protein thermostability: a unique N-terminal domain confers heat resistance to Fe/Mn-SODs.
abstract: Superoxide dismutases (SODs), especially thermostable SODs, are widely applied in medical treatments, cosmetics, food, agriculture, and other industries given their excellent antioxidant properties. A novel thermostable cambialistic SOD from Geobacillus thermodenitrificans NG80-2 exhibits maximum activity at 70 °C and high thermostability over a broad range of temperatures (20-80 °C). Unlike other reported SODs, this enzyme contains an extra repeat-containing N-terminal domain (NTD) of 244 residues adjacent to the conserved functional SODA domain. Deletion of the NTD dramatically decreased its optimum active temperature (OAT) to 30 °C and also impaired its thermostability. Conversely, appending the NTD to a mesophilic counterpart from Bacillus subtilis led to a moderately thermophilic enzyme (OAT changed from 30 to 55 °C) with improved heat resistance. Temperature-dependant circular dichroism analysis revealed the enhanced conformational stability of SODs fused with this NTD. Furthermore, the NTD also contributes to the stress resistance of host proteins without altering their metal ion specificity or oligomerisation form except for a slight effect on their pH profile. We therefore demonstrate that the NTD confers outstanding thermostability to the host protein. To our knowledge, this is the first discovery of a peptide capable of remarkably improving protein thermostability and provides a novel strategy for bioengineering thermostable SODs.
authors.affiliation: 1] Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China [2] Tianjin Key Laboratory of Microbial Functional Genomics, TEDA, Tianjin 300457, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: 1] Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China [2] College of Life Sciences, Nankai University, Tianjin 300071, PR China.
authors.forename: Ting
authors.initials: T
authors.lastname: Ma
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China.
authors.forename: Baoliang
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China.
authors.forename: Nana
authors.initials: N
authors.lastname: Yao
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China.
authors.forename: Mingchang
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China.
authors.forename: Lianlei
authors.initials: L
authors.lastname: Cui
authors.affiliation: 1] Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China [2] College of Life Sciences, Nankai University, Tianjin 300071, PR China.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Li
authors.affiliation: State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, PR China.
authors.forename: Zhenping
authors.initials: Z
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, PR China.
authors.forename: Jiansong
authors.initials: J
authors.lastname: Cheng
mesh_terms: D001412:Bacillus subtilis / Q000378:metabolism; D002942:Circular Dichroism; D056506:Geobacillus / Q000378:metabolism; D006358:Hot Temperature; D007501:Iron / Q000378:metabolism*; D008345:Manganese / Q000378:metabolism*; D055550:Protein Stability; D017434:Protein Structure, Tertiary / Q000502:physiology*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D008345:Manganese; D007501:Iron; D013482:Superoxide Dismutase