153 research outputs found
Domain dynamics of the Bacillus subtilis peripheral preprotein translocase subunit SecA
The homodimeric SecA protein is the peripheral subunit of the preprotein translocase in bacteria. It promotes the preprotein translocation across the cytoplasmic membrane by nucleotide-modulated co-insertion and de-insertion into the integral domain of the translocase. SecA has two essential nucleotide binding sites (NBS): the high-affinity NBS-I resides in the amino-terminal domain of the protein and the low-affinity NBS-II is localized at 2/3 of the protein sequence. The nucleotide bound states of soluble SecA were studied by differential scanning calorimetry (DSC). Thermal unfolding reveals that the amino- and carboxy-terminal halves of SecA unfold independently with a transition midpoint of 49 and 40 degrees C, respectively. Binding of ADP to NBS-I increased the interaction between the two domains, whereas binding of AMPPNP does not influence this interaction. When ADP binds both NBS-I and NBS-II, SecA seems to have a more compact globular conformation, whereas binding of AMP-PNP seems to cause a more extended conformation. It is concluded that SecA is a two-domain protein and that the interaction between both domains is modulated by nucleotides. The compact ADP-bound conformation may resemble the membrane-de-inserted state of SecA, while the more extended ATP bound conformation may correspond to the membrane-inserted form of SecA.</p
FUNCTIONAL RECONSTITUTION OF THE PURIFIED PHOSPHOENOLPYRUVATE-DEPENDENT MANNITOL-SPECIFIC TRANSPORT-SYSTEM OF ESCHERICHIA-COLI IN PHOSPHOLIPID-VESICLES - COUPLING BETWEEN TRANSPORT AND PHOSPHORYLATION
FUNCTIONAL RECONSTITUTION OF THE PURIFIED PHOSPHOENOLPYRUVATE-DEPENDENT MANNITOL-SPECIFIC TRANSPORT-SYSTEM OF ESCHERICHIA-COLI IN PHOSPHOLIPID-VESICLES - COUPLING BETWEEN TRANSPORT AND PHOSPHORYLATION
Liposome-Mediated Introduction of Foreign Proteins into the Matrix of Protoplasts and into the Peroxisomal Membrane of the Methanol-Grown Yeast Hansenula polymorpha
Liposome-Mediated Introduction of Foreign Proteins into the Matrix of Protoplasts and into the Peroxisomal Membrane of the Methanol-Grown Yeast Hansenula polymorpha
Liposome-Mediated Introduction of Foreign Proteins into the Matrix of Protoplasts and into the Peroxisomal Membrane of the Methanol-Grown Yeast Hansenula polymorpha
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