Mitochondria, chloroplasts and several species of bacteria have outer membrane proteins (OMPs) that perform many essential biological functions. The β‐barrel assembly machinery (BAM) complex is one of the OMPs of Borrelia burgdorferi, the pathogenic spirochete that causes Lyme disease, and its BamA component (BbBamA) includes a C‐terminal β‐barrel domain and five N‐terminal periplasmic polypeptide‐transport‐associated (POTRA) domains, which together perform a central transport function. In the current work, the production, crystallization and X‐ray analysis of the three N‐terminal POTRA domains of BbBamA (BbBamA‐POTRA P1–P3; residues 30–273) were carried out. The crystals of BbBamA‐POTRA P1–P3 belonged to space group P2₁, with unit‐cell parameters a = 45.353, b = 111.538, c = 64.376 Å, β = 99.913°. The Matthews coefficient was calculated to be 2.92 ų Da⁻¹, assuming the presence of two molecules per asymmetric unit, and the corresponding solvent content was 57.9%. Owing to the absence of an ideal homology model, numerous attempts to solve the BbBamA‐POTRA P1–P3 structure using molecular replacement (MR) failed. In order to solve the structure, further trials using selenomethionine derivatization are currently being carried out.

中文翻译：

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伯氏疏螺旋体β-桶装配机械A的结晶和X射线分析。

线粒体、叶绿体和多种细菌都具有执行许多重要生物学功能的外膜蛋白 (OMP)。β桶装配机械（BAM）复合体是伯氏疏螺旋体（引起莱姆病的致病性螺旋体）的OMP之一，其BamA成分（Bb BamA）包括一个C端β桶结构域和五个N端周质结构域。多肽转运相关（POTRA）结构域，它们共同执行中央转运功能。在当前的工作中，对Bb BamA的三个 N 端 POTRA 结构域（Bb BamA-POTRA P1-P3；残基 30-273）进行了生产、结晶和 X 射线分析。Bb BamA-POTRA P1-P3晶体属于P 2 ₁空间群，晶胞参数a = 45.353，b = 111.538，c = 64.376 Å，β = 99.913°。假设每个不对称单元存在两个分子，马修斯系数计算为2.92 Å ³  Da ^-1，相应的溶剂含量为57.9%。由于缺乏理想的同源模型，使用分子置换（MR）解决Bb BamA-POTRA P1-P3 结构的多次尝试都失败了。为了解析该结构，目前正在进行使用硒代蛋氨酸衍生化的进一步试验。