The dengue vector Aedes aegypti contains a functional high mobility group box 1 (HMGB1) protein with a unique regulatory C-terminus.
The mosquito Aedes aegypti can spread the dengue, chikungunya and yellow fever viruses. Thus, the search for key molecules involved in the mosquito survival represents today a promising vector control strategy. High Mobility Group Box (HMGB) proteins are essential nuclear factors that maintain the high-order structure of chromatin, keeping eukaryotic cells viable. Outside the nucleus, secreted HMGB proteins could alert the innate immune system to foreign antigens and trigger the initiation of host defenses. In this work, we cloned and functionally characterized the HMGB1 protein from Aedes aegypti (AaHMGB1). The AaHMGB1 protein typically consists of two HMG-box DNA binding domains and an acidic C-terminus. Interestingly, AaHMGB1 contains a unique alanine/glutamine-rich (AQ-rich) C-terminal region that seems to be exclusive of dipteran HMGB proteins. AaHMGB1 is localized to the cell nucleus, mainly associated with heterochromatin. Circular dichroism analyses of AaHMGB1 or the C-terminal truncated proteins revealed α-helical structures. We showed that AaHMGB1 can effectively bind and change the topology of DNA, and that the AQ-rich and the C-terminal acidic regions can modulate its ability to promote DNA supercoiling, as well as its preference to bind supercoiled DNA. AaHMGB1 is phosphorylated by PKA and PKC, but not by CK2. Importantly, phosphorylation of AaHMGB1 by PKA or PKC completely abolishes its DNA bending activity. Thus, our study shows that a functional HMGB1 protein occurs in Aedes aegypt and we provide the first description of a HMGB1 protein containing an AQ-rich regulatory C-terminus.
Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil.
Fabio Schneider
FS
Ribeiro
Isabel Caetano
IC
de Abreu da Silva
Vitor Coutinho
VC
Carneiro
Fabrício dos Santos
Fdos S
Belgrano
Ronaldo
R
Mohana-Borges
Ivone
I
de Andrade Rosa
Marlene
M
Benchimol
Nathalia Rocha Quintino
NR
Souza
Rafael Dias
RD
Mesquita
Marcos Henrique Ferreira
MH
Sorgine
Felipe
F
Gazos-Lopes
Amanda Roberta Revoredo
AR
Vicentino
Wenjie
W
Wu
Renata
R
de Moraes Maciel
Mario Alberto Cardoso
MA
da Silva-Neto
Marcelo Rosado
MR
Fantappié
D000330:Aedes; D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004278:DNA, Superhelical / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D024243:HMGB1 Protein / Q000737:chemistry* / Q000302:isolation & purification; D019476:Insect Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism
D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D024243:HMGB1 Protein; D019476:Insect Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C