Abstract
P5B ATPases are present in the genomes of diverse unicellular and multicellular eukaryotes, indicating that they have an ancient origin, and that they are important for cellular fitness. Inactivation of ATP13A2, one of the four human P5B ATPases, leads to early-onset Parkinson’s disease (Kufor-Rakeb Syndrome). The presence of an invariant PPALP motif within the putative substrate interaction pocket of transmembrane segment M4 suggests that all P5B ATPases might have similar transport specificity; however, the identity of the transport substrate(s) remains unknown. Nematodes of the genus Caenorhabditis possess three paralogous P5B ATPase genes, catp-5, catp-6 and catp-7, which probably originated from a single ancestral gene around the time of origin of the Caenorhabditid clade. By using CRISPR/Cas9, we have systematically investigated the expression patterns, subcellular localization and biological functions of each of the P5B ATPases of C. elegans. We find that each gene has a unique expression pattern, and that some tissues express more than one P5B. In some tissues where their expression patterns overlap, different P5Bs are targeted to different subcellular compartments (e.g., early endosomes vs. plasma membrane), whereas in other tissues they localize to the same compartment (plasma membrane). We observed lysosomal co-localization between CATP-6::GFP and LMP-1::RFP in transgenic animals; however, this was an artifact of the tagged LMP-1 protein, since anti-LMP-1 antibody staining of native protein revealed that LMP-1 and CATP-6::GFP occupy different compartments. The nematode P5Bs are at least partially redundant, since we observed synthetic sterility in catp-5(0); catp-6(0) and catp-6(0) catp-7(0) double mutants. The double mutants exhibit defects in distal tip cell migration that resemble those of ina-1 (alpha integrin ortholog) and vab-3 (Pax6 ortholog) mutants, suggesting that the nematode P5Bs are required for ina-1and/or vab-3 function. This is potentially a conserved regulatory interaction, since mammalian ATP13A2, alpha integrin and Pax6 are all required for proper dopaminergic neuron function.
Highlights
P-type ATPases are an ancient family of transmembrane proteins that use the energy derived from hydrolysis of ATP to actively transport substrates across membranes [1]
All three isoforms display the typical P5B ATPase structure: One membrane associated segment (Ma) [9], ten transmembrane segments (M1-M10), an actuator domain formed by two cytoplasmic loops, plus a nucleotide binding domain and a phosphorylation domain located in the large cytoplasmic loop (M4-M5, Fig 1, Fig 2B)
We do not know whether CATP-6b is expressed and/or functionally significant in vivo; the RNA seq data summarized on WormBase (WS262), suggest that catp-6b is not a highly-abundant transcript
Summary
P-type ATPases are an ancient family of transmembrane proteins that use the energy derived from hydrolysis of ATP to actively transport substrates across membranes [1]. These transporters have four types of structural domains (Fig 1, Fig 2B): the actuator domain (A), the nucleotide binding domain (N), the phosphorylation domain (P) and the transmembrane domain (M) [2]. The P-type ATPases can be grouped into 5 subfamilies, P1-P5 [4]. We focus on the P5B P-type ATPases, which have a putative substrate interaction motif of PPALP within transmembrane segment M4 [7,8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
