130 likes | 396 Views
Chemotaxis study. Chemotaxis in (some) bacteria. J. S. Parkinson, 2003. Our system: Thiomicrospira crunogena. Chemolithoautotroph *requirements for growth: O 2 , thiosulfate , CO 2 , ammonia or nitrate, phosphate Motile
E N D
Chemotaxis in (some) bacteria J. S. Parkinson, 2003
Our system: Thiomicrospiracrunogena Chemolithoautotroph *requirements for growth: O2, thiosulfate, CO2, ammonia or nitrate, phosphate Motile 14 methyl-accepting chemotaxis protein chemoreceptor genes *14 ‘noses’ to sense nutrients or toxins *5 PAS/PAC domain CRs: redox?
Objective • Identify what each CR binds Oxygen? Thiosulfate? Carbon dioxide? Ammonia? Nitrate? Phosphate? ??????? Parkinson lab, University of Utah
How to test each CR individually • Put the gene encoding each CR into a nonchemotactic strain of E. coli • See whether the E. coli becomes sensitive to a particular nutrient • May be possible to ‘pin’ a nutrient on a particular CR
Host and vector details • E. coli UU2612 host • All MCP genes gone • Motile but not chemotactic • pRR48 vector • AmpR • MCS behind a lacpromotor • ‘empty’ • ‘full’ • E. coli aer • T. cru
Steps • Purify genomic DNA from T. crunogena • Amplify CR genes via PCR • Ligate genes into pRR48 • Transform E. coli UU2612 with plasmids • Observe whether E. coli becomes aerotactic
Target genes and expression vector cut with restriction enzymes PCR product = copy of T. cru gene with sticky restriction enzyme-digested ends pRR48 expression plasmid
Target genes and expression vectorligated together PCR product = copy of T. cru gene with sticky restriction enzyme-digested ends pRR48 expression plasmid
Transformed competent E. coli with expression vector carrying target genes http://www.novasep.com/technologies/Upstream-expression-system.asp
Next step • Screen the E. coli carrying T. crunogenagenes for aerotactic behavior Redox?
Chemotaxis plates to assay motility • Details: • Low agar concentration • Succinate as sole carbon source