Fig. 3: Comparison between Adc and LdcI stack formation.
a Atomic model of two-decamer Adc and LdcI stacks. The closer packing of decamers in the LdcI stack reduces the repeat distance between decamers in the stack from 95 Å to 76 Å. b Close-up view of the decamer interfaces in the Adc stack and LdcI stack. Stack-forming residues are shown in magenta as sticks. The decamer:decamer interface in the Adc stack is equivalent to interface annotated ‘2’ in the LdcI stack, with an offset due to the inserted β-hairpin in Adc. This insertion, along with a 3-amino acid insertion at the end of α-helix α18, has the effect of pushing the decamers further apart in Adc with the consequence that there is no interface in Adc equivalent to interface ‘1’ in LdcI, reducing the total buried surface area between two decamers from 6108 Å2 to 1609 Å2. c Pairwise sequence alignment of LdcI and Adc in the beginning of the AAT-like domain, with insertions in Adc highlighted in green and red. The key stack-forming residues in Adc D472 and R492 are marked with an asterisk. d Monomeric structures of LdcI and Adc, with stack-forming residues shown in magenta as sticks. The Adc insertions highlighted in c are shown on the Adc structure in the same colours. e Conservation of the 14 residues involved in interfaces 1 and 2 of the LdcI stack formation across the Cluster II LdcIs represented as a sequence logo. The bar chart indicates the relative frequency of the consensus sequence residues. Residue numbers are from the E. coli LdcI sequence.
