Bacterial translation machinery for deliberate mistranslation of the genetic code

Inaccurate expression of the genetic code, also known as mistranslation, is an emerging paradigm in microbial studies. Growing evidence suggests that many microbial pathogens can deliberately mistranslate their genetic code to help invade a host or evade host immune responses. However, discovering different capacities for deliberate mistranslation remains a challenge because each group of pathogens typically employs a unique mistranslation mechanism. In this study, we address this problem by studying duplicated genes of aminoacyl-transfer RNA (tRNA) synthetases. Using bacterial prolyl-tRNA synthetase (ProRS) genes as an example, we identify an anomalous ProRS isoform, ProRSx, and a corresponding tRNA, tRNAProA, that are predominately found in plant pathogens from Streptomyces species. We then show that tRNAProA has an unusual hybrid structure that allows this tRNA to mistranslate alanine codons as proline. Finally, we provide biochemical, genetic, and mass spectrometric evidence that cells which express ProRSx and tRNAProA can translate GCU alanine codons as both alanine and proline. This dual use of alanine codons creates a hidden proteome diversity due to stochastic Ala→Pro mutations in protein sequences. Thus, we show that important plant pathogens are equipped with a tool to alter the identity of their sense codons. This finding reveals the initial example of a natural tRNA synthetase/tRNA pair for dedicated mistranslation of sense codons.

Mechanic’s hand; is it a prodromic sign of disease relapse of anti-synthetase syndrome; a case report

Background Anti-synthetase syndrome is the collection of myositis and/or interstitial lung disease with the presence of various antibodies directed against an aminoacyl transfer RNA synthetase. Anti Jo − 1 antibody is the commonest of these antibodies and its presence is characteristically associated with the dermatological manifestation of mechanic’s hands. However, in the absence of other features, whether the presence of mechanic’s hands could be considered as a prodromic sign of disease relapse is not proven. We would like to present a patient who developed mechanic’s hands and subsequently went on to have recurrence in her myositis. Case presentation A 45-year-old female initially presented with a progressive proximal muscle weakness. Her muscle enzymes were elevated, EMG and biopsy were also in keeping with an inflammatory myositis. Subsequently she was found to have an interstitial lung disease with a non-specific interstitial pneumonitis pattern radiologically. Her anti Jo-1 was positive. However, she did not have any dermatological manifestations at the time. With immunosuppressive therapy she achieved remission which lasted for about 2 years. Then she developed fissuring and cracking of the palms and fingers suggestive of mechanic’s hands without any muscle pain, weakness and elevation of muscle enzymes. A few months later she did develop muscle pain, weakness and elevation of muscle enzymes heralding a disease relapse. Conclusion The presence of mechanic’s hands without other features should be considered as a prodromic sign of disease relapse.

A case of macrophage activation syndrome in a patient with anti-synthetase syndrome

ABSTRACT Anti-synthetase syndrome (ASS) is an autoimmune disease characterized by autoantibodies against an aminoacyl transfer RNA synthetase with clinical features including interstitial lung disease, non-erosive arthritis, myositis, Raynaud’s phenomenon, unexplained fever and/or mechanic’s hands. Macrophage activation syndrome (MAS) is a potentially fatal hyper- inflammatory syndrome that can occur as a complication of systemic rheumatic diseases. However, the association of MAS and ASS has rarely been reported in the literature. Here, we report this association in a patient with overlap ASS and anti-CCP positive rheumatoid arthritis. First line management with steroids was complicated by diabetic ketoacidosis, hence requiring use of anti-IL1 therapy (anakinra) for disease control.

Single Nucleotide Polymorphism in the IL17A Gene Is Associated with Interstitial Lung Disease Positive to Anti-Jo1 Antisynthetase Autoantibodies

Antisynthetase syndrome (ASSD) is a rare multisystemic connective tissue disease affecting the skin, joints, muscles, and lungs, characterized by anti-aminoacyl transfer-RNA-synthetases (anti-tRNA) autoantibodies production, being anti-Jo1 the most frequent. We included one-hundred twenty-one ASSD patients and 340 healthy subjects (HS), and also, we divided the case group into anti-Jo1 and non-anti-Jo1. Two single nucleotide polymorphisms (SNPs) in the IL17A gene were evaluated. Anti-Jo1 was the most common anti-tRNA antibody in our cohort, and the most frequent tomographic pattern was non-specific interstitial pneumonia (NSIP). Anti-Jo1 ASSD patients had higher levels of creatine phosphokinase than the non-anti-Jo1 group. Significant differences in genotype frequencies with rs8193036/CC between anti-Jo1 vs. non-anti-Jo1 ASSD patients (p < 0.001), maintaining the association after Bonferroni correction (p = 0.002). Additionally, in the anti-Jo1 group vs. HS comparison, we found a statistically significant difference with the same SNP (p = 0.018, OR = 2.91, 95% CI = 1.15–7.35), maintaining the association after Bonferroni correction (p = 0.036). The rs8193036/CC genotype in IL17A is associated with ASSD patients with anti-Jo1. Also, anti-Jo1 and non-anti-Jo1 patients display differences in genotype frequencies.

Antisynthetase Syndrome associated with mycobacterium tuberculosis infection, presenting as an acute respiratory failure

Antisynthetase syndrome (ASS) is characterized by myositis, interstitial lung disease, Raynaud’s phenomenon, fever and mechanics hands. Diagnosis is confirmed with the detection of an antibody directed against anti–aminoacyl–transfer–RNA synthetases (ARS). The most common anti–ARS antibody is anti–Jo–1. Opportunistic infections are common causes of mortality in patients with autoimmune diseases. Immunosuppressive treatment further contributes to the risk of infection. We report a rare case of a 68 year–old man diagnosed with antisynthetase syndrome associated to a pulmonary tuberculosis infection, revealed with an acute respiratory failure. The diagnosis of this rare combination of a connective tissue disease and tuberculosis revealed with an acute respiratory failure is difficult in a previously asymptomatic patient. Early diagnosis and immunosuppressive therapy associated to antituberculosis treatment started precociously prevented the disease progression and resulted in a good outcome.

A translation-independent function of PheRS activates growth and proliferation in Drosophila

ABSTRACTAminoacyl transfer RNA (tRNA) synthetases (aaRSs) not only load the appropriate amino acid onto their cognate tRNAs, but many of them also perform additional functions that are not necessarily related to their canonical activities. Phenylalanyl tRNA synthetase (PheRS/FARS) levels are elevated in multiple cancers compared to their normal cell counterparts. Our results show that downregulation of PheRS, or only its α-PheRS subunit, reduces organ size, whereas elevated expression of the α-PheRS subunit stimulates cell growth and proliferation. In the wing disc system, this can lead to a 67% increase in cells that stain for a mitotic marker. Clonal analysis of twin spots in the follicle cells of the ovary revealed that elevated expression of the α-PheRS subunit causes cells to grow and proliferate ∼25% faster than their normal twin cells. This faster growth and proliferation did not affect the size distribution of the proliferating cells. Importantly, this stimulation proliferation turned out to be independent of the β-PheRS subunit and the aminoacylation activity, and it did not visibly stimulate translation.This article has an associated First Person interview with the joint first authors of the paper.

Anti-synthetase syndrome: a rare and challenging diagnosis for bilateral ground-glass opacities—a case report with literature review

Background Anti-synthetase syndrome (ASS) is an uncommon immune-mediated entity characterized by myositis, interstitial lung disease (ILD), non-erosive arthritis, and less common features such as fever, Raynaud’s phenomenon, and skin changes in association with anti-aminoacyl-transfer-RNA antibodies, most commonly anti-Jo-1 antibodies. Case presentation We present a challenging and rare case of ASS-associated ILD presenting with unexplained respiratory symptoms and bilateral infiltrates on chest imaging during the COVID-19 pandemic. High clinical suspicion for ASS with early appropriate therapy with corticosteroids and immunosuppressive agents led to marked clinical improvement. Conclusion High index of suspicion for ASS is mandated in patients with unexplained ILD. A comprehensive autoimmune work-up is important as an early treatment with corticosteroids with or without immunomodulators improves patient outcomes and survival in an otherwise poor prognostic disease.