Noncanonical DNA polymerization by aminoadenine-based siphoviruses

Bacteriophage genomes harbor the broadest chemical diversity of nucleobases across all life forms. Certain DNA viruses that infect hosts as diverse as cyanobacteria, proteobacteria, and actinobacteria exhibit wholesale substitution of aminoadenine for adenine, thereby forming three hydrogen bonds with thymine and violating Watson-Crick pairing rules. Aminoadenine-encoded DNA polymerases, homologous to the Klenow fragment of bacterial DNA polymerase I that includes 3'-exonuclease but lacks 5'-exonuclease, were found to preferentially select for aminoadenine instead of adenine in deoxynucleoside triphosphate incorporation templated by thymine. Polymerase genes occur in synteny with genes for a biosynthesis enzyme that produces aminoadenine deoxynucleotides in a wide array of Siphoviridae bacteriophages. Congruent phylogenetic clustering of the polymerases and biosynthesis enzymes suggests that aminoadenine has propagated in DNA alongside adenine since archaic stages of evolution.

AB0451 PRIMARY SJOGREN’S SYNDROME IN MEN

Background:

Primary Sjogren’s syndrome (PSS) is characterized as an autoimmune exocrinopathy, but this disorder also may involve extraglandular organs, giving rise to multisystem disease. Although the first case reported by Dr Mikulicz was a 42 year old man [1], there are only few reports describing the clinical picture of Sjogren’s Syndrome in males

Objectives:

To determine whether there were any clinical and biological differences between male and female tunisian patients with primary Sjogren’s syndrome (PSS).

Methods:

We studied 60 patients with pSS according to American-European Consensus Group (AECG), attending an Internal Medicine departement in Tunisia. The nine (15%) male patients in this cohort comprised the male group described in this study

Results:

The average age of men at diagnosis was 53.2 years [31 to 73 years]. Male SSp was revealed by sicca symptoms (55.5%), by extra glandular manifestations (33.3%). Fourty-four percent of our male patients had a positive result for a minor salivary gland biopsy (grade III or IV).

Extraglandular manifestations during the course of the disease were present in 6 cases (66%) of our male patients with pSS. weight loss and raynaud’s phenomenon were more common in men. a significantly greater percentage of men had neurological involvement (66.6%vs 23,7) and and pulmonary involvement, notably a restrictive syndrome (66.6% vs 31,1%, p=0.043). The positivity of Anti-nuclear antibodies, anti-SSb and rheumatoid factor were significantly less common in males.

Anemia was significanty more common in the male patients (p=0,049). No cases of Lymphoma in the male patients in our series.

Eighty-eight percent of the men were treated with corticosteroids. In our series, the use of immunosuppressants was not necessary in male patients.

Conclusion:

Although pSS is typically a disease affecting women, clinicians should be aware that it may be diagnosed in male patients. Although men were at the same risk for the development of extraglandular complications, there were significant serologic and immunogenetic differences. In Sharp contrast to women with Sjogren’s syndrome, men with Sjogren’s syndrome were more seronegative in our series.

References:

[1]Mikulicz J. Discussion at Verein fur wissenschaftliche Heilkunde zu königsberg. Berl Klin Wocchenschr 1888; 25:759.

[2]Gondran G, Fauchais A, Lambert M, Ly K, Launay D, Queyrel V, et al. Primary Sjogren’s syndrome in men. Scandinavian journal of rheumatology. 2008;37(4):300-5.

[3]Virdee S, Greenan-Barrett J, Ciurtin C. A systematic review of primary Sjogren’s syndrome in male and paediatric populations. 2017;36(10):2225-36

Disclosure of Interests:

None declared

Invading Escherichia coli Genetics with a Xenobiotic Nucleic Acid Carrying an Acyclic Phosphonate Backbone (ZNA)

A synthetic orthogonal polymer embracing a chiral acyclic-phosphonate backbone [(S)-ZNA] is presented that uniquely adds to the emerging family of xenobiotic nucleic acids (XNAs). (S)-ZNA consists of reiterating six-atom structural units and can be accessed in few synthetic steps from readily available phophonomethylglycerol nucleoside (PMGN) precursors. Comparative thermal stability experiments conducted on homo- and heteroduplexes made of (S)-ZNA are described that evince its high self-hybridization efficiency in contrast to poor binding of natural complements. Although preliminary and not conclusive, circular dichroism data and dynamic modeling computations provide support to a left-handed geometry of double-stranded (S)-ZNA. Nonetheless, PMGN diphosphate monomers were recognized as substrates by Escherichia coli (E. coli) polymerase I as well as being imported into E. coli cells equipped with an algal nucleotide transporter. A further investigation into the in vivo propagation of (S)-ZNA culminated with the demonstration of the first synthetic nucleic acid with an acyclic backbone that can be transliterated to DNA by the E. coli cellular machinery.