Editing ATPase (section)

==Structure==
The [[Walker motifs]] are a telltale protein sequence motif for nucleotide binding and hydrolysis.  Beyond this broad function, the Walker motifs can be found in almost all natural ATPases, with the notable exception of [[tyrosine kinase]]s.<ref name="pmid6329717">{{cite journal |vauthors=Walker JE, Saraste M, Runswick MJ, Gay NJ |title=Distantly related sequences in the alpha- and beta-subunits of ATP synthase, myosin, kinases and other ATP-requiring enzymes and a common nucleotide binding fold |journal=EMBO J. |volume=1 |issue=8 |pages=945–51 |year=1982 |pmid=6329717 |pmc=553140 |doi= 10.1002/j.1460-2075.1982.tb01276.x}}</ref> The Walker motifs commonly form a [[Beta sheet]]-turn-[[Alpha helix]] that is self-organized as a [[Nest (protein structural motif)]].  This is thought to be because modern ATPases evolved from small NTP-binding peptides that had to be self-organized.<ref name="Romero RomeroYang2018">{{cite journal | vauthors = Romero Romero ML, Yang F, Lin YR, Toth-Petroczy A, Berezovsky IN, Goncearenco A, Yang W, Wellner A, Kumar-Deshmukh F, Sharon M, Baker D, Varani G, Tawfik DS | display-authors = 6 | title = Simple yet functional phosphate-loop proteins | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 115 | issue = 51 | pages = E11943–E11950 | date = December 2018 | pmid = 30504143 | doi = 10.1073/pnas.1812400115 | pmc = 6304952 | doi-access = free }}</ref>

[[Protein design]] has been able to replicate the ATPase function (weakly) without using natural ATPase sequences or structures.  Importantly, while all natural ATPases have some beta-sheet structure, the designed "Alternative ATPase" lacks beta sheet structure, demonstrating that this life-essential function is possible with sequences and structures not found in nature.<ref name="WangHecht2020">{{cite journal | vauthors = Wang M, Hecht MH | title = A Completely De Novo ATPase from Combinatorial Protein Design | journal = Journal of the American Chemical Society | date = August 2020 | volume = 142 | issue = 36 | pages = 15230–15234 | pmid = 32833456 | doi = 10.1021/jacs.0c02954 }}</ref>