Subcellular localization of the <i>Synechocystis</i> Deg proteases.

<p>(A) Total wild-type cell extract and a PSII-enriched fraction isolated from the HT3 strain of <i>Synechocystis</i> 6803 were analyzed by SDS-PAGE, and by immunostaining using antibodies directed against recombinant HhoA, HhoB, or HtrA. Of the total cell extract, samples corresponding to 0.1 µg of chlorophyll were loaded for immunostaining with anti-HhoA and samples corresponding to 0.5 µg were loaded for anti-HhoB and anti-HtrA. Of the PSII-enriched fraction, samples corresponding to 5 µg of chlorophyll were loaded in each lane. (B) Outer membrane (OM), plasma membrane (PM), thylakoid membrane (TM), and soluble protein fraction (S) were isolated from <i>Synechocystis</i> 6803 by gradient centrifugation and two-phase partitioning, separated by SDS-PAGE, and immunostained using antibodies directed against recombinant HhoA, HhoB, or HtrA. Purity of the membranes was determined by using antibodies directed against the PSII protein CP47 and against NrtA, a component of the nitrate transporter; 15 µg of protein was loaded in each lane.