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The role of Tyr41 and His155 in the functional properties of superoxide dismutase from the Archaeon Sulfolobus solfataricus

Gogliettino, MA; Tanfani, F; Scire, A; Ursby, Thomas LU ; Adinolfi, BS; Cacciamani, T and De Vendittis, E (2004) In Biochemistry 43(8). p.2199-2208
Abstract
We have examined and compared the effects of mutating Y41 and H155 in the iron superoxide dismutase (SOD) from the archaeon Sulfolobus solfataricus (Ss). These two neighboring residues in the active site are known to have crucial functions in structurally related SODs from different sources. The metal analysis indicates a slightly lower iron content after either Y41F or H155Q replacement, without any significant substitution of iron for manganese. The specific activity of SsSOD referred to the iron content is 17-fold reduced in the Y41F mutant, whereas it is less than 2-fold reduced by the H155Q mutation. The noticeable pH dependence of the activity of SsSOD and H155Q-SsSOD, due to the ionization of Y41 (pK 8.4), is lost in Y41F-SsSOD.... (More)
We have examined and compared the effects of mutating Y41 and H155 in the iron superoxide dismutase (SOD) from the archaeon Sulfolobus solfataricus (Ss). These two neighboring residues in the active site are known to have crucial functions in structurally related SODs from different sources. The metal analysis indicates a slightly lower iron content after either Y41F or H155Q replacement, without any significant substitution of iron for manganese. The specific activity of SsSOD referred to the iron content is 17-fold reduced in the Y41F mutant, whereas it is less than 2-fold reduced by the H155Q mutation. The noticeable pH dependence of the activity of SsSOD and H155Q-SsSOD, due to the ionization of Y41 (pK 8.4), is lost in Y41F-SsSOD. After H155Q and even more after the Y41F substitution, the archaeal enzyme acquires a moderate sensitivity to sodium azide inhibition. The hydrogen peroxide inactivation of SsSOD is significantly increased after H155Q replacement; however, both mutants are insensitive to the modification of residue 41 by phenylmethanesulfonyl fluoride. Heat inactivation studies showed that the high stability of SsSOD is reduced by the H155Q mutation; hovewer, upon the addition of SDS, a much faster inactivation kinetics is observed both with wild-type and mutant SsSOD forms. The detergent is also required to follow thermal denaturation of the archaeal enzyme by Fourier transform infrared spectroscopy; these studies gave information about the effect of mutations and modification on flexibility and compactness of the protein structure. The crystal structure of Y41F mutant revealed an uninterrupted hydrogen bond network including three solvent molecules connecting the iron-ligating hydroxide ion via H155 with F41 and H37, which is not present in structures of the corresponding mutant SODs from other sources. These data suggest that Y41 and H155 are important for the structural and functional properties of SsSOD; in particular, Y41 seems to be a powerful regulator of the activity of SsSOD, whereas H155 is apparently involved in the organization of the active site of the enzyme. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biochemistry
volume
43
issue
8
pages
2199 - 2208
publisher
The American Chemical Society
external identifiers
  • wos:000189185700007
  • pmid:14979716
  • scopus:1442276493
ISSN
0006-2960
DOI
10.1021/bi035661y
language
English
LU publication?
yes
id
1acc9e58-d725-4b32-b6fb-7e32c16ab819 (old id 286814)
date added to LUP
2007-10-29 08:55:23
date last changed
2017-01-01 04:33:21
@article{1acc9e58-d725-4b32-b6fb-7e32c16ab819,
  abstract     = {We have examined and compared the effects of mutating Y41 and H155 in the iron superoxide dismutase (SOD) from the archaeon Sulfolobus solfataricus (Ss). These two neighboring residues in the active site are known to have crucial functions in structurally related SODs from different sources. The metal analysis indicates a slightly lower iron content after either Y41F or H155Q replacement, without any significant substitution of iron for manganese. The specific activity of SsSOD referred to the iron content is 17-fold reduced in the Y41F mutant, whereas it is less than 2-fold reduced by the H155Q mutation. The noticeable pH dependence of the activity of SsSOD and H155Q-SsSOD, due to the ionization of Y41 (pK 8.4), is lost in Y41F-SsSOD. After H155Q and even more after the Y41F substitution, the archaeal enzyme acquires a moderate sensitivity to sodium azide inhibition. The hydrogen peroxide inactivation of SsSOD is significantly increased after H155Q replacement; however, both mutants are insensitive to the modification of residue 41 by phenylmethanesulfonyl fluoride. Heat inactivation studies showed that the high stability of SsSOD is reduced by the H155Q mutation; hovewer, upon the addition of SDS, a much faster inactivation kinetics is observed both with wild-type and mutant SsSOD forms. The detergent is also required to follow thermal denaturation of the archaeal enzyme by Fourier transform infrared spectroscopy; these studies gave information about the effect of mutations and modification on flexibility and compactness of the protein structure. The crystal structure of Y41F mutant revealed an uninterrupted hydrogen bond network including three solvent molecules connecting the iron-ligating hydroxide ion via H155 with F41 and H37, which is not present in structures of the corresponding mutant SODs from other sources. These data suggest that Y41 and H155 are important for the structural and functional properties of SsSOD; in particular, Y41 seems to be a powerful regulator of the activity of SsSOD, whereas H155 is apparently involved in the organization of the active site of the enzyme.},
  author       = {Gogliettino, MA and Tanfani, F and Scire, A and Ursby, Thomas and Adinolfi, BS and Cacciamani, T and De Vendittis, E},
  issn         = {0006-2960},
  language     = {eng},
  number       = {8},
  pages        = {2199--2208},
  publisher    = {The American Chemical Society},
  series       = {Biochemistry},
  title        = {The role of Tyr41 and His155 in the functional properties of superoxide dismutase from the Archaeon Sulfolobus solfataricus},
  url          = {http://dx.doi.org/10.1021/bi035661y},
  volume       = {43},
  year         = {2004},
}