6IXI

structure of Cd-bound periplasmic metal binding protein from candidatus liberibacter asiaticus

Summary for 6IXI

• Entry DOI: 10.2210/pdb6ixi/pdb
• Descriptor: Periplasmic solute binding protein, CADMIUM ION, GLYCEROL, ... (6 entities in total)
• Functional Keywords: candidatus liberibacter asiaticus, periplasmic, metal binding protein
• Biological source: Candidatus Liberibacter asiaticus str. psy62
• Total number of polymer chains: 1
• Total formula weight: 32713.52

Authors

Kumar, P.,Sharma, N.,Dalal, V.,Ghosh, D.K.,Kumar, P.,Sharma, A.K. (deposition date: 2018-12-10, release date: 2020-01-15, Last modification date: 2023-11-22)

Primary citation

Kumar, P.,Dalal, V.,Sharma, N.,Kokane, S.,Ghosh, D.K.,Kumar, P.,Sharma, A.K.
Characterization of the heavy metal binding properties of periplasmic metal uptake protein CLas-ZnuA2.
Metallomics, 12:280-289, 2020

PubMed Abstract: Candidatus Liberibacter asiaticus (CLas), a phloem-limited unculturable Gram-negative bacterium, causes citrus greening disease. The proteome analysis of CLas showed the presence of a heavy metal permease and Co/Zn/Cd cation exporter system. However, there is no designated metal uptake protein specific for the heavy metal permease in CLas. One of the metal uptake proteins, designated as CLas-ZnuA2, in our previous studies, showed a lower metal-binding affinity for Mn2+ and Zn2+ and was postulated to bind and transport metals rather non-specifically. The present study focused on the characterization of the heavy metal binding properties of CLas-ZnuA2 using SPR, CD, DSC and crystallographic studies. The crystal structure analysis of Cd2+ bound CLas-ZnuA2 showed octahedral geometry for Cd2+ binding as compared to a non-preferred square-pyramidal geometry for Mn2+ and Zn2+ binding in earlier reported crystal structures. In SPR analysis, the binding affinities of 4.7 × 10-6 M, 7.2 × 10-6 M, 5.3 × 10-5 M and 4.3 × 10-5 M for Hg2+, Cd2+, Ba2+ and Co2+ respectively were higher as compared to earlier reported values for Mn2+ and Zn2+. Likewise, CD and DSC analysis showed relatively higher thermal stability for CLas-ZnuA2 on heavy metal binding. Taken together with the expression of the permease and exporter system for heavy metals, our results indicate that CLas-ZnuA2 may be involved in sequestering and transport of various transition divalent metals in environmentally stressed conditions.

PubMed: 31853532
DOI: 10.1039/c9mt00200f

Experimental method

X-RAY DIFFRACTION (2.07 Å)