bacterial proteases? - (Jun/10/2007 )
I would like to know how a toxin or antibiotic produced inside bacteria gets out of the cell, thought cell wall? Is my assumption that bacteria have proteases correct?
And, mitochondria are of Gram +ve origin, yes? Is it known how it developed double membrane, or am I a bit ignorant?
thanks
No. Current understanding points toward mitochondia decending from a subdivision of the α-proteobacteria that contains Rickettsia and certain other obligate intracellular parasites. α-proteobacteria are all gram negative.
The wall structure of the bacterium has little to do with the double membrane structure. The double membrane structure hint that something with its own membrane has been engulfed by the cell.
well it depends on which toxin but generally it should be soluble through the cell wall. ABC transporter for example can acts as carrier for toxin through the cell wall by binding to the toxin.
The type of protease will dictate how it gets out of the cell. For gram negative bacteria, type 1 or 2 secretion systems can be used with multiple cleavage of signal peptides along the way. Thermolysin of Pseudomonas secretes itself through the outer membrane with the signal peptide playing a role in inactivation, or in many cases they just don't know how the proteases are secreted as there is no apparent sequence directing them to specific systems.
oh...i think ive got an idea...is it bcos tat the bacteria has a membrane transport system using the carrier ionophore and the channel-forming ionophore?
An axample of carrier ionophore is Valinomycin. i juz checked out w my biochem textbk... 