Identification of a Novel Sequence Motif Recognized by the Ankyrin Repeat Domain of zDHHC17/13 S-Acyltransferases*

Abstract

Background: S-Acylation, a protein lipidation process that is essential for neuronal functions, is catalyzed by zDHHC S-acyltransferases.

Results: The ankyrin repeat (AR) domains of zDHHC17 and zDHHC13 recognize a novel unstructured peptide sequence in several unrelated proteins.

Conclusion: Several proteins have independently acquired similar short peptide sequences for zDHHC17/13 binding.

Significance: This is the first study to identify a motif recognized by AR-containing S-acyltransferases.

Abstract

S-Acylation is a major post-translational modification affecting several cellular processes. It is particularly important for neuronal functions. This modification is catalyzed by a family of transmembrane S-acyltransferases that contain a conserved zinc finger DHHC (zDHHC) domain. Typically, eukaryote genomes encode for 7–24 distinct zDHHC enzymes, with two members also harboring an ankyrin repeat (AR) domain at their cytosolic N termini. The AR domain of zDHHC enzymes is predicted to engage in numerous interactions and facilitates both substrate recruitment and S-acylation-independent functions; however, the sequence/structural features recognized by this module remain unknown. The two mammalian AR-containing S-acyltransferases are the Golgi-localized zDHHC17 and zDHHC13, also known as Huntingtin-interacting proteins 14 and 14-like, respectively; they are highly expressed in brain, and their loss in mice leads to neuropathological deficits that are reminiscent of Huntington's disease. Here, we report that zDHHC17 and zDHHC13 recognize, via their AR domain, evolutionary conserved and closely related sequences of a [VIAP][VIT] XXQP consensus in SNAP25, SNAP23, cysteine string protein, Huntingtin, cytoplasmic linker protein 3, and microtubule-associated protein 6. This novel AR-binding sequence motif is found in regions predicted to be unstructured and is present in a number of zDHHC17 substrates and zDHHC17/13-interacting S-acylated proteins. This is the first study to identify a motif recognized by AR-containing zDHHCs.