Materials Science Japan Advanced Institute of Science and Technology Masaru KAWAKAMI
Here we show a new protein molecular model of SecDF. This new model is called kawakami-model, designed by Dr. Kawakami, a member of the Executive Committee. In bacteria, SecDF, a pair of membrane integrated Sec factors, play important roles in efficient protein export in vivo. It contains 12 transmembrane helices and 2 large periplasmic domains (P1 and P4). It is proposed that SecDF interacts with a protein conducting channel (translocon), captures a substrate polypeptide emerging from the translocon by its P1 head sub-domain and undergoes conformational changes of the P1domain using the proton motive force to facilitate forward movement of the polypeptide. This new handleable protein molecular model has a soft and transparent silicone body similar to the molecule's surface. A main chain structure embedded in the body enables users to feel the molecular surface and view through the main chain structure. In addition, essential amino acid residues for the flow of protons located within SecD-SecF transmembrane interfaces can be seen through the body. The characteristics of this SecDF model is its "changeable" P1 domain , from F- to I - form, representing different conformational states of SecDF. This interactive, hands-on model may deepen the user’s understanding of the structure of SecDF and would be very useful for its peer discussions.
Nature 474, 235–238 (09 June 2011)
Rev. Sci. Instrum. 83, 084303 (2012)
(2013.03.15)