The ROK kinase N-acetylglucosamine kinase uses a sequential random enzyme mechanism with successive conformational changes upon each substrate binding.

N-acetyl-d-glucosamine (GlcNAc) is a major component of bacterial cell walls. Many organisms recycle GlcNAc from the cell wall or metabolize environmental GlcNAc. The first step in GlcNAc metabolism is phosphorylation to GlcNAc-6-phosphate. In bacteria, the ROK family kinase N-acetylglucosamine kinase (NagK) performs this activity. Although ROK kinases have been studied extensively, no ternary complex showing the two substrates has yet been observed. Here, we solved the structure of NagK from the human pathogen Plesiomonas shigelloides in complex with GlcNAc and the ATP analog AMP-PNP. Surprisingly, PsNagK showed distinct conformational changes associated with the binding of each substrate. Consistent with this, the enzyme showed a sequential random enzyme mechanism. This indicates that the enzyme acts as a coordinated unit responding to each interaction. Our molecular dynamics modeling of catalytic ion binding confirmed the location of the essential catalytic metal. Additionally, site-directed mutagenesis confirmed the catalytic base and that the metal-coordinating residue is essential. Together, this study provides the most comprehensive insight into the activity of a ROK kinase.

Rapid functionalisation and detection of viruses via a novel Ca2+-mediated virus-DNA interaction.

Current virus detection methods often take significant time or can be limited in sensitivity and specificity. The increasing frequency and magnitude of viral outbreaks in recent decades has resulted in an urgent need for diagnostic methods that are facile, sensitive, rapid and inexpensive. Here, we describe and characterise a novel, calcium-mediated interaction of the surface of enveloped viruses with DNA, that can be used for the functionalisation of intact virus particles via chemical groups attached to the DNA. Using DNA modified with fluorophores, we have demonstrated the rapid and sensitive labelling and detection of influenza and other viruses using single-particle tracking and particle-size determination. With this method, we have detected clinical isolates of influenza in just one minute, significantly faster than existing rapid diagnostic tests. This powerful technique is easily extendable to a wide range of other enveloped pathogenic viruses and holds significant promise as a future diagnostic tool.

Urogenital and caudal dysgenesis in adrenocortical dysplasia (acd) mice is caused by a splicing mutation in a novel telomeric regulator.

Adrenocortical dysplasia (acd) is a spontaneous autosomal recessive mouse mutant with developmental defects in organs derived from the urogenital ridge. In surviving adult mutants, adrenocortical dysplasia and hypofunction are predominant features. Adults are infertile due to lack of mature germ cells, and 50% develop hydronephrosis due to ureteral hyperplasia. We report the identification of a splice donor mutation in a novel gene, which is the mouse ortholog of a newly discovered telomeric regulator. This gene (Acd) has recently been characterized as a novel component of the TRF1 protein complex that controls telomere elongation by telomerase. Characterization of Acd transcripts in mutant animals reveals two abnormal transcripts, consistent with a splicing defect. Expression of a wild-type Acd transgene in acd mutants rescues the observed phenotype. Most mutants die within 1-2 days of life on the original genetic background. Analysis of these mutant embryos reveals variable, yet striking defects in caudal specification, limb patterning and axial skeleton formation. In the tail bud, reduced expression of Wnt3a and Dll1 correlates with phenotypic severity of caudal regression. In the limbs, expression of Fgf8 is expanded in the dorsal-ventral axis of the apical ectodermal ridge and shortened in the anterior-posterior axis, consistent with the observed loss of anterior digits in older embryos. The axial skeleton of mutant embryos shows abnormal vertebral fusions in cervical, lumbar and caudal regions. This is the first report to show that a telomeric regulator is required for proper urogenital ridge differentiation, axial skeleton specification and limb patterning in mice.