Figure 4 | Scientific Reports

Figure 4

From: Structure of polyhydroxyalkanoate (PHA) synthase PhaC from Chromobacterium sp. USM2, producing biodegradable plastics

Figure 4

Conformational changes in the CAP subdomain as revealed by structural comparison of PhaC Cs -CAT and PhaC Cn -CAT structures. (a) A side-view of the overlay between PhaC Cs -CAT (cyan and magenta) and PhaC Cn -CAT (gray and yellow) with an overall r.m.s. deviation of 2.7 Å for Cα carbon atoms. The major conformational deviations are observed in part of the CAP subdomain, the LID region (residues Pro327–Pro386 in magenta) of PhaC Cs -CAT, which corresponds to the segment Thr355–Pro419 (yellow) of PhaC Cn -CAT. Arrows indicate conformational transitions of the LID region from PhaC Cs -CAT to PhaC Cn -CAT. (b) As in a, but a top-view down to the active site. A narrow path to the active site was found in PhaC Cn -CAT, whereas the path is covered by the LID region in PhaC Cs -CAT. (c) To clarify the conformational transitions found by the structural comparison of PhaC Cs -CAT and PhaC Cn -CAT, overlay of the LID regions of the two structures are shown. Unfolding of ηA, αA and ηB helices of PhaC Cs -CAT into a long flexible D-loop found in PhaC Cn -CAT is indicated by magenta arrows, and refolding of αB’ and ηB’ helices and their linker loop of PhaC Cs -CAT into a long α4 helix in PhaC Cn -CAT by red arrows. The disulfide bond between Cys328 and Cys438 of PhaC Cn -CAT is shown in green.

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