Biology subjects

Greive, S. J.

Publications and source records attributed to Greive, S. J..

2 recordsLinked to original sources

bioRxiv2023

Structure of HK97 small terminase:DNA complex unveils a novel DNA binding mechanism by a circular protein.

DNA recognition is critical for assembly of double-stranded DNA viruses, in particular for the initiation of packaging the viral genome into the capsid. DNA packaging has been extensively studied for three archetypal bacteriophage systems: cos, pac and phi29. We identified the minimal site within the cos region of bacteriophage HK97 specifically recognised by the small terminase and determined a cryoEM structure for the small terminase:DNA complex. This nonameric circular protein utilizes a previously unknown mechanism of DNA binding. While DNA threads through the central tunnel, unexpectedly, DNA-recognition is generated at its exit by a substructure formed by the N- and C-terminal segments of two adjacent protomers of the terminase which are unstructured in the absence of DNA. Such interaction ensures continuous engagement of the small terminase with DNA, allowing sliding along DNA while simultaneously checking the DNA sequence. This mechanism allows locating and instigating packaging initiation and termination precisely at the cos site.

biochemistry↗

bioRxiv2020

CryoEM structure of the Nipah virus nucleocapsid assembly

Nipah virus is a highly pathogenic zoonotic RNA virus, causing fatal encephalitis in humans. Like other negative-strand RNA viruses including Ebola and measles, its genome is wrapped by the nucleocapsid (N) protein forming a helical assembly. Here we report the CryoEM structure of the Nipah nucleocapsid protein-RNA assembly, at near atomic resolution. The N protein wraps the RNA genome with a periodicity of six nucleotides per protomer, around the outer edge of the helical assembly, in common with other paramyxoviruses. This structure uncovers details of the nucleocapsid assembly, demonstrating the role of the N-terminal arm of the N protein in the formation of the helical assembly and revealing details of the sequence-independent coordination of RNA binding in the "3-bases-in, 3-bases-out" conformation. CryoEM analysis also reveals formation of clam-shaped assemblies of the N-protein, mediated by intersubunit interactions involving several N protein loop regions.

biophysics↗