Atomic force and super-resolution microscopy support a role for LapA as a cell-surface biofilm adhesin of Pseudomonas fluorescens.
Pseudomonas fluorescence Pf0-1 requires the large repeat protein LapA for stable surface attachment. This study presents direct evidence that LapA is a cell-surface-localized adhesin. Atomic force microscopy (AFM) revealed a significant 2-fold reduction in adhesion force for mutants lacking the LapA protein on the cell surface compared to the wild-type strain. Deletion of lapG, a gene encoding a periplasmic cysteine protease that functions to release LapA from the cell surface, resulted in a 2-fold increase in the force of adhesion. Three-dimensional structured illumination microscopy (3D-SIM) revealed the presence of the LapA protein on the cell surface, consistent with its role as an adhesin. The protein is only visualized in the cytoplasm for a mutant of the ABC transporter responsible for translocating LapA to the cell surface. Together, these data highlight the power of combining the use of AFM and 3D-SIM with genetic studies to demonstrate that LapA, a member of a large group of RTX-like repeat proteins, is a cell-surface adhesin.
Department of Chemical Engineering, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, USA. ieivanov@stanford.edu
Ivan E
IE
Ivanov
Chelsea D
CD
Boyd
Peter D
PD
Newell
Mary E
ME
Schwartz
Lynne
L
Turnbull
Michael S
MS
Johnson
Cynthia B
CB
Whitchurch
George A
GA
O'Toole
Terri A
TA
Camesano
D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development*; D017353:Gene Deletion; D037102:Lectins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008853:Microscopy / Q000379:methods; D011551:Pseudomonas fluorescens / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D037102:Lectins; D008565:Membrane Proteins; C038692:adhesin, Pseudomonas