Substrate recruitment by zDHHC protein acyltransferases

Abstract

Protein palmitoylation is the post-translational attachment of fatty acids, most commonly palmitate (C16 : 0), onto a cysteine residue of a protein. This reaction is catalysed by a family of integral membrane proteins, the zDHHC protein acyltransferases (PATs), so-called due to the presence of an invariant Asp–His–His–Cys (DHHC) cysteine-rich domain harbouring the catalytic centre of the enzyme. Conserved throughout eukaryotes, the zDHHC PATs are encoded by multigene families and mediate palmitoylation of thousands of protein substrates. In humans, a number of zDHHC proteins are associated with human diseases, including intellectual disability, Huntington's disease, schizophrenia and cancer. Key to understanding the physiological and pathophysiological importance of individual zDHHC proteins is the identification of their protein substrates. Here, we will describe the approaches and challenges in assigning substrates for individual zDHHCs, highlighting key mechanisms that underlie substrate recruitment.

Synaptic Activity-Dependent Changes in the Hippocampal Palmitoylome

“…When examining gene expression using the DropViz hippocampal single-cell RNAseq database, we found that 10 of the 30 palmitoylating/ de-palmitoylating enzymes and accessory proteins were predominantly enriched in neurons and also highly co-expressed with neuron-enriched differentially palmitoylated proteins from our screen. ZDHHC enzymes in this subset are thought to localize to a variety of subcellular domains, including the Golgi (ZDHHC3, ZDHHC13, ZDHHC17, ZDHHC21, ZDHHC23) and postsynapse (ZDHHC2, ZDHHC5, ZDHHC8) (Malgapo & Linder, 2021;Solis, Valnohova, Alvarez, & Katanaev, 2020). We found that a substantial proportion of the differentially palmitoylated substrates identified in our screen localize at the preand/or postsynapse, making ZDHHC2, ZDHHC5 and ZDHHC8 well positioned to mediate postsynaptic increases in substrate palmitoylation in response to plasticity-inducing stimuli.…”

Function of Protein S-Palmitoylation in Immunity and Immune-Related Diseases

“…The biomedical importance of PATs and APTs is underscored by their involvement in a variety of human diseases and this has aroused a growing interest in palmitoylation regulatory mechanisms ( 19 , 203 ). Despite recent advances in understanding the mechanism and regulation of both PATs and APTs, many critical issues remain.…”

A sticky situation: regulation and function of protein palmitoylation with a spotlight on the axon and axon initial segment

“…The DHHC active site motif catalyzes palmitoylation and the CRD coordinates two zinc atoms in a zinc-finger motif, crucial for structural stability [ 49–53 ]. The PAT gene family is conserved throughout eukaryotes and the 23 mammalian ZDHHC PATs demonstrate distinct but overlapping substrate specificity [ 16 , 54 ].…”

“…Additionally, proteins that contain multiple palmitoylation sites can be modified at different intracellular locations by various PATs [ 57 , 58 ]. PATs are integral membrane proteins that contain four to six transmembrane domains with the conserved DHHC-CRD oriented to face the cytosol [ 16 , 59 ]. In addition to the DHHC-CRD, PATs have three other conserved motifs.…”

“…Despite the high similarity of the DHHC-CRD among the PATs, the N- and C-termini of these enzymes are poorly conserved, having diverse sequences and sizes contributing to substrate selectivity [ 16 , 54 ]. ZDHHC13 and ZDHHC17 have N-terminal ankyrin repeat domains that interact with many of their substrates’ zDHHC ankyrin-binding motifs to allow palmitoylation [ 62–67 ].…”