Dynamic Filament Formation by a Divergent Bacterial Actin-Like ParM Protein.
Actin-like proteins (Alps) are a diverse family of proteins whose genes are abundant in the chromosomes and mobile genetic elements of many bacteria. The low-copy-number staphylococcal multiresistance plasmid pSK41 encodes ParM, an Alp involved in efficient plasmid partitioning. pSK41 ParM has previously been shown to form filaments in vitro that are structurally dissimilar to those formed by other bacterial Alps. The mechanistic implications of these differences are not known. In order to gain insights into the properties and behavior of the pSK41 ParM Alp in vivo, we reconstituted the parMRC system in the ectopic rod-shaped host, E. coli, which is larger and more genetically amenable than the native host, Staphylococcus aureus. Fluorescence microscopy showed a functional fusion protein, ParM-YFP, formed straight filaments in vivo when expressed in isolation. Strikingly, however, in the presence of ParR and parC, ParM-YFP adopted a dramatically different structure, instead forming axial curved filaments. Time-lapse imaging and selective photobleaching experiments revealed that, in the presence of all components of the parMRC system, ParM-YFP filaments were dynamic in nature. Finally, molecular dissection of the parMRC operon revealed that all components of the system are essential for the generation of dynamic filaments.
School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia.
Anthony J
AJ
Brzoska
School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia.|School of Medicine, Ingham Institute for Applied Medical Research, University of Western Sydney, Sydney, NSW, 1871, Australia.
Slade O
SO
Jensen
School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia.
Deborah A
DA
Barton
School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia.
Danielle S
DS
Davies
School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia.
Robyn L
RL
Overall
School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia.
Ronald A
RA
Skurray
School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia.
Neville
N
Firth
D008841:Actin Cytoskeleton / Q000235:genetics*; D000199:Actins / Q000096:biosynthesis / Q000235:genetics*; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D008164:Luminescent Proteins; D008856:Microscopy, Fluorescence; D009876:Operon / Q000235:genetics; D061848:Optical Imaging; D010957:Plasmids / Q000235:genetics*; D013211:Staphylococcus aureus / Q000235:genetics*
D000199:Actins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008164:Luminescent Proteins; C471255:ParM protein, E coli; C054562:yellow fluorescent protein, Bacteria