New insights into the domain of unknown function (DUF) of EccC5, the pivotal ATPase providing the secretion driving force to the ESX-5 secretion system

Ceballos-Zúñiga, F.; Menéndez, M.; Pérez-Dorado, I.

doi:10.1107/S2059798324004248

Figure 2
(a) A general view of the $[Mtb{\rm EccC_5^{DUF}}]$ crystal structure represented as green cartoons is shown (left), as well as details of the putative ATP-binding site (right). Salt-bridge and hydrogen-bond interactions are indicated as dashed lines in blue and black, respectively, as well as the bond distances between Arg227 and Asp328. The Walker A, Walker B and Sensor 1 motifs are coloured blue, pink and orange, respectively, showing key residues (sticks) and water molecules (red spheres). A scheme with details of the regions of $[Mtb{\rm EccC_5^{DUF}}]$ included in the crystallographic construct is shown. (b) Sequence alignment of the Walker A and Walker B motifs of $[Mtb{\rm EccC_5^{DUF}}]$ with the canonical ATPase domains of PrgFtsK, SslHerA, PfrMCM, MsdVps4 and $[Mtb{\rm EccC_{1-5}^{D1}}]$ , showing the consensus sequence at the top. Key amino acids involved in nucleotide interaction/hydrolysis are highlighted in blue and pink, respectively. (c) Superimposition of the $[Mtb{\rm EccC_5^{DUF}}]$ and PrgFtsK (PDB entry 4r7y, beige) structures represented as cartoons. The Walker A, Walker B and Sensor 1 motifs are coloured light blue, pink and orange, respectively, in $[Mtb{\rm EccC_5^{DUF}}]$ and in dark teal, purple and dark orange, respectively, in PrgFtsK. In PrgFtsK, the magnesium cation is represented as a green sphere, while ATP (in black) and residues key to the interaction with the nucleotide are represented as sticks. The Arg227–Asp328 salt bridge observed in $[Mtb{\rm EccC_5^{DUF}}]$ and the hydrogen bonds involved in ATP/Mg²⁺ stabilization in PrgFtsK are represented as dashed lines in blue and black, respectively. (d) Detail of the Walker A motif in $[Mtb{\rm EccC_5^{DUF}}]$ and PrgFtsK, showing the favourable dihedral angle C_i—N_i+1— $[{\rm C}^{\alpha}_{i+1}]$ — $[{\rm C}^{\beta}_{i+1}]$ observed between Glu228 and Gln229 in the former compared with the nonfavourable dihedral angle generated between Ser470 and Gly471 of PrgFtsK when the glycine is substituted by an alanine.

STRUCTURAL
BIOLOGY

ISSN: 2059-7983

Volume 80| Part 6| June 2024| Pages 397-409

https://doi.org/10.1107/S2059798324004248

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