2 component regulatory systems Maltose=effector, BUT if signal not DIRECTLY involved, but needs to be transmitted and changed = signal transduction Sensor protein= –kinase, phosphorylates compounds, –membrane associated Phosphoryl group transmitted to another regulator IN the cell –Often a DNA binding protein involved in transcription Many examples, N-fixation, sporulation,chemotaxis

Chemotaxis Attractants decrease rate of autophosphorylation Repellant increased autophosphorylation CheA-CheW=transducer CheY controls switch –cheY-P tumbles, CCW-CW CheB phosporylated by CheA-P, but slower response than CheY-P CheB involved methylation –Fully methylated = best for repellants –cheB-P demethylates, occurs when attractants High –Degree of methylation regulates attraction/repulsion

Chemotaxis

Genetic exchange: transformation

Genetic exchange: plasmid transfer Small, usually circular, independently replicating DNA molecules –Generally, G - plasmids replicate as does chromosomal DNA, G + plasmids by “rolling circle” replication Genes of replication control, timing initiation on plasmid (ori) –Some plasmids integrate (F +, Hfr) –Most are double-stranded –About kb Code for: –R-factors (R-plasmids) : antibiotic resistance, heavy metal resistance –Virulence plasmids : adhesins, hemolytic factors, toxin, Ti, bacteriocins –Degradation, tol, nah, Plasmid copy # Compatibility (inc)

Genetic exchange: plasmid transfer Small, usually circular, independently replicating DNA molecules –Generally, G - plasmids replicate as does chromosomal DNA, G + plasmids by “rolling circle” replication Genes of replication control, timing initiation on plasmid (ori) –Some plasmids integrate (F +, Hfr) –Most are double-stranded –About kb Code for: –R-factors (R-plasmids) : antibiotic resistance, heavy metal resistance –Virulence plasmids : adhesins, hemolytic factors, toxin, Ti, bacteriocins –Degradation, tol, nah, Plasmid copy # Compatibility (inc)

Avery Experiment

Transformation Competence: ability to be transformed Steps in transformation –DNA binding and uptake (SS or DS, depending on species) –Integration (recA) Competence may be induced by electroporation, Ca

Mechanism of transformation

Transduction Generalized— low frequency Specialized— high frequency:requires specific integration

Generalized transduction

Specialized transduction

Genetic exchange: conjugation

Conjugation: early Cell-surface structure

Conjugation: middle

Conjugation: late

Genetic Engineering-basics Basic steps in cloning –Restriction-modification enzymes –“shot gun” or PCR –Ligase –Recombination Plasmids (or phage)= vectors –Expression vectors Selection of clones Looking for a clone with a specific gene –Probes (DNA, RNA or antibody) Wave of the future: DNA chips or “microarrays”, BAC libraries, automated sequencing etc

Genomics Bioinformatics Harvesting genes for biotech (Diversa) –Recent Science article Comparing gene families