Six specific lysine residues are crucial in maintaining the structure and function of soluble manganese stabilizing protein.
When manganese stabilizing protein (MSP) was treated with 0.5 mM N-succinimidyl propionate (NSP), the rebinding ability and oxygen-releasing capabilities of the modified MSP were not altered, in spite of changes of MSP surface Lys residues. Furthermore, far-ultraviolet circular dichroism and intrinsic fluorescence spectra analysis revealed that 0.5 mM NSP-modified MSP retained most of its native secondary and tertiary structure. Mapping of the sites of NSP modification by Staphylococcus V(8) protease digestion of the modified protein, as well as analysis by matrix-assisted laser desorption ionization-time of flight mass spectrometry, indicated that seven Lys residues were modified. The results suggested that these residues are not absolutely essential to the structure and function of MSP. However, when the NSP concentration was increased to 4 mM, the modified MSP was unable to bind photosystem II and completely lost its reactivating capability. Both far-ultraviolet circular dichroism and intrinsic fluorescence spectra analysis revealed a clear conformational change in MSP after 4 mM NSP treatment, suggesting that some Lys residues are involved in maintaining the structure and function of MSP. Analysis by matrix-assisted laser desorption ionization-time of flight mass spectrometry indicated that another six Lys residues, namely Lys20, Lys101, Lys196, Lys207, Lys130 (or Lys137) and Lys66 (or Lys76), were modified by 4 mM NSP. Therefore, these six Lys residues are crucial in maintaining the structure and function of soluble MSP.
Gao
Jin-Peng
JP
Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
Zhang
Feng
F
Zhang
Li
L
Guo
Yin-Long
YL
Ruan
Kang-Cheng
KC
Jiang
De-An
DA
Xu
Chun-He
CH
D001665:Binding Sites; D008239:Lysine / Q000737:chemistry*; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D011485:Protein Binding; D012995:Solubility; D013329:Structure-Activity Relationship
D045332:Photosystem II Protein Complex; C054266:photosystem II manganese-stabilizing protein; D008239:Lysine