Electrostatic analysis of bacterial expansins.
Expansins are a family of proteins with plant cell wall remodeling-activity, which bind cell wall components through hydrophobic and electrostatic interactions. A shallow area on the surface of the protein serves as the polysaccharide binding site (PBS) and it is composed of conserved residues. However, electric charge differences on the opposite face of the PBS produce basic, neutral, or acidic proteins. An analysis of forty-four bacterial expansins, homologues of BsEXLX1, revealed two main groups defined by: (a) the presence or absence of disulfide bonds; and (b) by the proteins isoelectric point (pI). We determined the location of the residues responsible for the pI on the structure of representative expansins. Our results suggest that the electric charge at the opposite site of the PBS may help in substrate differentiation among expansins from different species; in addition, electrostatic polarization between the front and the back of the molecule could affect expansin activity on cellulose.
Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Cuernavaca, 62209, Morelos, México.
Nina
N
Pastor
Sonia
S
Dávila
Ernesto
E
Pérez-Rueda
Lorenzo
L
Segovia
Claudia
C
Martínez-Anaya
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D017124:Conserved Sequence; D004563:Electrochemistry; D007526:Isoelectric Point; D008958:Models, Molecular; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D020539:Sequence Analysis, Protein; D013499:Surface Properties
D001426:Bacterial Proteins; D010940:Plant Proteins; C095825:expansin protein, plant
cellulose; electric charge; expansins; isoelectric point; plant cell wall