Revised Mimivirus major capsid protein sequence reveals intron-containing gene structure and extra domain.
BACKGROUND
Acanthamoebae polyphaga Mimivirus (APM) is the largest known dsDNA virus. The viral particle has a nearly icosahedral structure with an internal capsid shell surrounded with a dense layer of fibrils. A Capsid protein sequence, D13L, was deduced from the APM L425 coding gene and was shown to be the most abundant protein found within the viral particle. However this protein remained poorly characterised until now. A revised protein sequence deposited in a database suggested an additional N-terminal stretch of 142 amino acids missing from the original deduced sequence. This result led us to investigate the L425 gene structure and the biochemical properties of the complete APM major Capsid protein.


RESULTS
This study describes the full length 3430 bp Capsid coding gene and characterises the 593 amino acids long corresponding Capsid protein 1. The recombinant full length protein allowed the production of a specific monoclonal antibody able to detect the Capsid protein 1 within the viral particle. This protein appeared to be post-translationnally modified by glycosylation and phosphorylation. We proposed a secondary structure prediction of APM Capsid protein 1 compared to the Capsid protein structure of Paramecium Bursaria Chlorella Virus 1, another member of the Nucleo-Cytoplasmic Large DNA virus family.


CONCLUSIONS
The characterisation of the full length L425 Capsid coding gene of Acanthamoebae polyphaga Mimivirus provides new insights into the structure of the main Capsid protein. The production of a full length recombinant protein will be useful for further structural studies.
Azza
Saïd
S
Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), CNRS-IRD UMR 6236, IFR 48, Faculté de Médecine, 27 Boulevard Jean Moulin, 13385 Marseille cedex 05, France. said.azza@univmed.fr
Cambillau
Christian
C
Raoult
Didier
D
Suzan-Monti
Marie
M
D000595:Amino Acid Sequence; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004267:DNA Viruses / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D007438:Introns; D008969:Molecular Sequence Data; D015394:Molecular Structure; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D036022:Capsid Proteins; D014764:Viral Proteins