Atypical Genetic Basis of Pyrazinamide Resistance in Monoresistant Mycobacterium tuberculosis.
Atypical Genetic Basis of Pyrazinamide Resistance in Monoresistant Mycobacterium tuberculosis.
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DOI：
10.1128/aac.01916-20
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发表时间：
2021-05-18
影响因子：
4.9
通讯作者：
Valafar F
中科院分区：
文献类型：
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作者：
Modlin SJ;Marbach T;Werngren J;Mansjö M;Hoffner SE;Valafar F
吡嗪酰胺（PZA）是一种广泛应用的抗结核药物。通常，PZA抗性（PZA-R）出现在对异烟肼和利福平具有抗性的结核分枝杆菌菌株中（即，多药耐药[MDR]），并由抑制转化为其活性形式吡嗪酸（POA）的功能丧失型pncA突变所赋予。PZA-R偏离了这个典型的场景，人们对此知之甚少。在这里，我们基因分型pncA和声称替代PZA-R基因（panD，rpsA，clpC 1）与长读段测序的19个表型PZA单耐药分离株收集在瑞典，并比较其系统发育和基因组特征的MDR PZA-R（MDRPZA-R）的一大套分离株。我们报告了临床分离株中ClpC 1启动子（clpC 1 p −138）和ClpC 1 N末端（ClpC 1Val 63 Ala）的ClpC 1突变与PZA-R的首次关联。突变已经出现在这两个地区的POA选择在体外，和ClpC 1的N-末端区域已被牵连进一步，通过其POA依赖性的功效在PanD蛋白水解。ClpC 1Val 63 Ala突变体跨越4个印度洋亚系。印度洋分离株总是携带ClpC 1Val 63 Ala，并且与MDRPZA-R分离株（5/80）相比，在PZA单一耐药分离株（11/19）中明显过高（比值比[OR] = 22.2，P < 0.00001）。印度洋分离株在PZA单耐药结核病（TB）中过度表达的遗传基础尚未确定，但大量间接证据表明ClpC 1Val 63 Ala赋予低水平的PZA耐药性。我们的研究结果强调ClpC 1与PZA-R具有潜在的临床相关性，并加强了遗传背景在耐药性发展轨迹中的重要性。
Pyrazinamide (PZA) is a widely used antitubercular chemotherapeutic. Typically, PZA resistance (PZA-R) emerges in Mycobacterium tuberculosis strains with existing resistance to isoniazid and rifampin (i.e., multidrug resistance [MDR]) and is conferred by loss-of-function pncA mutations that inhibit conversion to its active form, pyrazinoic acid (POA). PZA-R departing from this canonical scenario is poorly understood. Here, we genotyped pncA and purported alternative PZA-R genes (panD, rpsA, and clpC1) with long-read sequencing of 19 phenotypically PZA-monoresistant isolates collected in Sweden and compared their phylogenetic and genomic characteristics to a large set of MDR PZA-R (MDRPZA-R) isolates. We report the first association of ClpC1 mutations with PZA-R in clinical isolates, in the ClpC1 promoter (clpC1p−138) and the N terminus of ClpC1 (ClpC1Val63Ala). Mutations have emerged in both these regions under POA selection in vitro, and the N-terminal region of ClpC1 has been implicated further, through its POA-dependent efficacy in PanD proteolysis. ClpC1Val63Ala mutants spanned 4 Indo-Oceanic sublineages. Indo-Oceanic isolates invariably harbored ClpC1Val63Ala and were starkly overrepresented (odds ratio [OR] = 22.2, P < 0.00001) among PZA-monoresistant isolates (11/19) compared to MDRPZA-R isolates (5/80). The genetic basis of Indo-Oceanic isolates’ overrepresentation in PZA-monoresistant tuberculosis (TB) remains undetermined, but substantial circumstantial evidence suggests that ClpC1Val63Ala confers low-level PZA resistance. Our findings highlight ClpC1 as potentially clinically relevant for PZA-R and reinforce the importance of genetic background in the trajectory of resistance development.