Structure of a C-terminal AHNAK peptide in a 1:2:2 complex with S100A10 and an acetylated N-terminal peptide of annexin A2

Abstract

AHNAK, a large 629 kDa protein, has been implicated in membrane repair, and the annexin A2–S100A10 heterotetramer [(p11)2(AnxA2)2)] has high affinity for several regions of its 1002‐amino‐acid C‐terminal domain. (p11)2(AnxA2)2 is often localized near the plasma membrane, and this C2‐symmetric platform is proposed to be involved in the bridging of membrane vesicles and trafficking of proteins to the plasma membrane. All three proteins co‐localize at the intracellular face of the plasma membrane in a Ca2+‐dependent manner. The binding of AHNAK to (p11)2(AnxA2)2 has been studied previously, and a minimal binding motif has been mapped to a 20‐amino‐acid peptide corresponding to residues 5654–5673 of the AHNAK C‐terminal domain. Here, the 2.5 Å resolution crystal structure of this 20‐amino‐acid peptide of AHNAK bound to the AnxA2–S100A10 heterotetramer (1:2:2 symmetry) is presented, which confirms the asymmetric arrangement first described by Rezvanpour and coworkers and explains why the binding motif has high affinity for (p11)2(AnxA2)2. Binding of AHNAK to the surface of (p11)2(AnxA2)2 is governed by several hydrophobic interactions between side chains of AHNAK and pockets on S100A10. The pockets are large enough to accommodate a variety of hydrophobic side chains, allowing the consensus sequence to be more general. Additionally, the various hydrogen bonds formed between the AHNAK peptide and (p11)2(AnxA2)2 most often involve backbone atoms of AHNAK; as a result, the side chains, particularly those that point away from S100A10/AnxA2 towards the solvent, are largely interchangeable. While the structure‐based consensus sequence allows interactions with various stretches of the AHNAK C‐terminal domain, comparison with other S100 structures reveals that the sequence has been optimized for binding to S100A10. This model adds new insight to the understanding of the specific interactions that occur in this membrane‐repair scaffold.

Comprehensive Proteomic and Metabolomic Signatures of Nontypeable Haemophilus influenzae-Induced Acute Otitis Media Reveal Bacterial Aerobic Respiration in an Immunosuppressed Environment

“…Plastins further participate in cell invasion by the intracellular pathogens Salmonella and Shigella (100). Similarly, AHNAK complexes with actin, S100A10 and annexin A2 to mediate architectural remodeling of the cell membrane and cortical cytoskeleton to promote invasion of Salmonella into epithelial cells (100,(102)(103)(104)(105). We hypothesize that the increased levels of these actin-associated proteins suggest actin remodeling enhances recruitment of immune cells and invasion of epithelial cells.…”

Plasma membrane and cytoskeleton dynamics during single-cell wound healing

“…The membranes of enlargeosome have been shown to be resistant to the detergent Triton X-100, and to be rich in cholesterol and sphingolipids [130] Fusion of enlargeosomes with the plasmalemma has been shown to be dependent on VAMP4 and to involve Syntaxin-6 and SNAP-23 [135]. Enlargeosomes may also interact with the plasmalemma via AHANK, as it is known to bind the membrane S100A10:annexin II heterotetramer (2:2) [136] in a Ca 2+ -dependent manner [137,138]. These observations are somewhat problematic, as prior to Ca 2+ -stimulation, AHNAK is found in the luminal-face of enlargeosomes [139].…”

“…[49] S100 family S100A10 a -S100A10 depleted cells show increased cell damage and reduced membrane repair. [136][137][138] S100A11 -S100A11 mutants unable to bind annexin II show diminished plasmalemma repair and survival in a cellular model of invasive cancer. [51] Others…”

Protective Function of Ahnak1 in Vascular Healing after Wire Injury

“…Through interaction with dysferlin, Ahnak1 has been linked to muscle repair mechanisms and muscular dystrophy [21,39]. Furthermore, Ahnak1 participates in the tetrameric annexin2/S100A10 complex [1,18,19,20], indicative of a potential role in fibrolysis, migration, and neoangiogenesis [43]. Annexin2/S100A10 complexes are essential components of caveolin-enriched microdomains that play a pivotal role in high molecular weight-hyaluronan (HMW-HA)/CD44-triggered endothelial barrier formation [44].…”

“…Redundancy of both proteins might explain the overt normal development of Ahnak1-deficient mice [16]. However, the nonhomologous carboxy-terminal domain of Ahnak1, in particular, has been shown to have specific functions and interaction partners such as the actin-based cytoskeleton [17], the annexinA2/S100A10 complex [1,18,19,20], dysferlin [21], formin-like 1 protein (FMNL1) [22], and the β-subunit of the L-type Ca 2+ channel [23]. As a component of the L-type Ca 2+ channel complex, Ahnak1 participates in Ca 2+ handling in T cells [24], cardiomyocytes [23], and osteoblasts [25].…”