RESUMEN
ABBA was reported to be an actin dynamics regulator. However, the molecular mechanism of action of ABBA is still totally obscure. Here, we show that ABBA is ubiquitously expressed in all the examined cultured cells. We found that expression of ABBA in NIH3T3 cells promotes cell spreading. ABBA binds to and markedly promotes cell spreading-induced Rac1 activation. Cell spreading stimulates ABBA activation probably by inducing it tyrosine phosphorylation, which endows ABBA much higher activity to activate Rac1, and attenuates the interaction between ABBA and Rac1. Loss of function suggests that deletion of ABBA in C6-R cells markedly inhibits Rac1 activation and cell spreading; this suggests that and the interaction between ABBA and activated Rac1 is required for ABBA-promoted cell spreading. Taken together, our results indicate that ABBA is activated in response to cell spreading, which markedly promotes cell spreading, and ABBA is required for Rac1 activation and cell spreading.
Asunto(s)
Movimiento Celular , Fibronectinas/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas de Microfilamentos/metabolismo , Proteínas de Neoplasias/metabolismo , Neuropéptidos/metabolismo , Proteínas de Unión al GTP rac/metabolismo , Animales , Forma de la Célula , Activación Enzimática , Técnicas de Silenciamiento del Gen , Proteínas Fluorescentes Verdes/metabolismo , Células HeLa , Humanos , Proteínas de la Membrana/genética , Ratones , Proteínas de Microfilamentos/genética , Células 3T3 NIH , Proteínas de Neoplasias/genética , Neuropéptidos/genética , Fosforilación , Unión Proteica , Mapeo de Interacción de Proteínas , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Transfección , Tirosina/metabolismo , Proteínas de Unión al GTP rac/genética , Proteína de Unión al GTP rac1RESUMEN
The scorpion venom peptides with no disulfide bridge are rarely identified and poorly characterized so far. Here, we report the identification and characterization of four novel disulfide-bridge-free venom peptides (BmKa1, BmKa2, BmKb1 and BmKn2) from Buthus martensii Kasch. BmKa1 and BmKa2 are very acidic and hydrophilic, showing no any similarity to other proteins, whereas BmKb1 and BmKn2 both are basic, alpha-helical peptide with an amidated C-terminus, showing a little homology with other peptides. Functional tests with synthetic peptide showed that BmKn2 has strong antimicrobial activity against both Gram-positive and Gram-negative bacteria, whereas BmKb1 has weak activity in inhibiting the growth of these bacteria.
Asunto(s)
Péptidos Catiónicos Antimicrobianos/química , Biología Computacional , Disulfuros/química , Biblioteca de Genes , Venenos de Escorpión/química , Secuencia de Aminoácidos , Animales , Datos de Secuencia Molecular , Escorpiones/metabolismo , Homología de Secuencia de AminoácidoRESUMEN
A novel cDNA sequence encoding a new type of scorpion venom peptide (BmKAPi) was first isolated from the venom gland of Buthus martensii Karsch by cDNA library screening combined with 5'-race. The encoded precursor of BmKAPi consisted of 89 amino acid residues including a signal peptide of 24 residues, a putative mature peptide of 64 residues (BmKAPi) and an extra basic residue at the C-terminus which might be removed in the post-translational processing. BmKAPi is stabilized by five disulfide bridges, whereas all other disulfide-bridged scorpion toxins described are cross-linked by three or four disulfide bridges. It suggested the three-dimensional scaffold of BmKAPi might be different from other scorpion toxins. The amino acid sequence of BmKAPi showed no homology with other scorpion venom peptides, but shared a little similarity with some anticoagulant peptides and proteinase inhibitors isolated from hookworm, honeybee or European frog, respectively. RT-PCR analysis showed that BmKAPi mRNA could be induced by venom extraction suggesting BmKAPi might be a component of scorpion venom. These results suggest that BmKAPi is a new type of scorpion venom peptide different from other described scorpion toxins in structural and functional aspects.