Identification of the critical structural determinants of the EF-hand domain arrangements in calcium binding proteins

Genome-wide identification of CML gene family in Salix matsudana and functional verification of SmCML56 in tolerance to salts tress

Calmodulin-like protein (CML) mediates Ca2+ signaling in response to abiotic stress. It has been shown that manipulating this signaling can improve crop stress resistance. However, the CML family in Willow has not been comprehensively and deeply studied. In this study, 157 SmCML genes were identified on the whole genome of Salix matsudana using bioinformatics method. Phylogenetic analysis showed that CML homologs between S. matsudana and Arabidopsis thaliana shared close relationships. The identified SmCML genes were distributed on 41 chromosomes. Analysis of cis-acting elements indicated that SmCMLs play an important role in plant hormone signal transduction and environmental stress response. SmCML56 gene was successfully cloned from S. matsudana and overexpressed in A. thaliana was constructed by flower dip method, and overexpressed in willow was constructed by Agrobacterium rhizogenes K599 mediated genetic transformation of willow hairy roots. Phenotypic, physiological and biochemical analysis confirmed that overexpression of SmCML56 significantly increased the tolerance of plants to salt. At the same time, VIGS experiment showed that the tolerance of silenced plants to salt stress decreased. The results of this study increased the understanding and characterization of SmCML genes in willow and will be a rich resource for further studies to investigate SmCML protein function in various developmental processes of willow. It provided a reference for related calmodulin-like studies in other perennial species.

Peptides derived from transcription factor EB bind to calcineurin at a similar region as the NFAT-type motif

Calcineurin (CN) is involved in many physiological processes and interacts with multiple substrates. Most of the substrates contain similar motifs recognized by CN. Recent studies revealed a new CN substrate, transcription factor EB (TFEB), which is involved in autophagy. We showed that a 15-mer QSYLENPTSYHLQQS peptide from TFEB (TFEB-YLENP) bound to CN. When the TFEB-YLENP peptide was changed to YLAVP, its affinity for CN increased and it had stronger CN inhibitory activity. Molecular dynamics simulations revealed that the TFEB-YLENP peptide has the same docking sites in CN as the 15-mer DQYLAVPQHPYQWAK motif of the nuclear factor of activated T cells, cytoplasmic 1 (NFATc1-YLAVP). Moreover expression of the NFATc1-YLAVP peptide suppressed the TFEB activation in starved Hela cells. Our studies first identified a CN binding site in TFEB and compared the inhibitory capability of various peptides derived from CN substrates. The data uncovered a diversity in recognition sequences that underlies the CN signaling within the cell. Studies of CN-substrate interactions should lay the groundwork for developing selective CN peptide inhibitors that target CN-substrate interaction in vitro experiments.

Spectrin and phospholipids - the current picture of their fascinating interplay

The spectrin-based membrane skeleton is crucial for the mechanical stability and resilience of erythrocytes. It mainly contributes to membrane integrity, protein organization and trafficking. Two transmembrane protein macro-complexes that are linked together by spectrin tetramers play a crucial role in attaching the membrane skeleton to the cell membrane, but they are not exclusive. Considerable experimental data have shown that direct interactions between spectrin and membrane lipids are important for cell membrane cohesion. Spectrin is a multidomain, multifunctional protein with several distinctive structural regions, including lipid-binding sites within CH tandem domains, a PH domain, and triple helical segments, which are excellent examples of ligand specificity hidden in a regular repetitive structure, as recently shown for the ankyrin-sensitive lipid-binding domain of beta spectrin. In this review, we summarize the state of knowledge about interactions between spectrin and membrane lipids.