The concept of biomedical significance of the functional pairing between tissue lectins and their glycoconjugate counterreceptors has reached the mainstream of research on the flow of biological information. A major challenge now is to identify the principles of structure-activity relationships that underlie specificity of recognition and the ensuing post-binding processes. Toward this end, we focus on a distinct feature on the side of the lectin, i.e. its architecture to present the carbohydrate recognition domain (CRD). Working with a multifunctional human lectin, i.e. galectin-3, as model, its CRD is used in protein engineering to build variants with different modular assembly. Hereby, it becomes possible to compare activity features of the natural design, i.e. CRD attached to an N-terminal tail, with those of homo- and heterodimers and the tail-free protein. Thermodynamics of binding disaccharides proved full activity of all proteins at very similar affinity. The following glycan array testing revealed maintained preferential contact formation with N-acetyllactosamine oligomers and histo-blood group ABH epitopes irrespective of variant design. The study of carbohydrate-inhibitable binding of the test panel disclosed up to qualitative cell-type-dependent differences in sections of fixed murine epididymis and especially jejunum. By probing topological aspects of binding, the susceptibility to inhibition by a tetravalent glycocluster was markedly different for the wild-type vs the homodimeric variant proteins. The results teach the salient lesson that protein design matters: the type of CRD presentation can have a profound bearing on whether basically suited oligosaccharides, which for example tested positively in an array, will become binding partners in situ. When lectin-glycoconjugate aggregates (lattices) are formed, their structural organization will depend on this parameter. Further testing (ga)lectin variants will thus be instrumental (i) to define the full range of impact of altering protein assembly and (ii) to explain why certain types of design have been favored during the course of evolution, besides opening biomedical perspectives for potential applications of the novel galectin forms.

中文翻译：

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蛋白质（人半乳糖凝集素3）设计对凝集素活性的影响。

组织凝集素与其糖缀合物抗受体之间功能配对的生物医学意义的概念已成为生物学信息流研究的主流。现在的主要挑战是确定结构-活性关系的原理，这些原理是识别的特异性和随后的结合后过程的基础。为此，我们将重点放在凝集素一侧的独特功能上，即呈现碳水化合物识别结构域（CRD）的结构。它的CRD与多功能人凝集素（即半乳凝素3）协同工作，可用于蛋白质工程中，以构建具有不同模块组装的变体。因此，可以比较自然设计的活动特征，即连接到N末端尾巴的CRD，同型和异型二聚体以及无尾蛋白 结合二糖的热力学证明所有蛋白都具有非常相似的亲和力。以下聚糖阵列测试表明，与变体设计无关，与N-乙酰基乳糖胺低聚物和组织血型ABH表位保持了优先接触。测试小组对碳水化合物的抑制性结合研究表明，在固定的小鼠附睾，尤其是空肠的切片中，细胞的类型依赖于定性差异。通过探测结合的拓扑学方面，对于野生型与同源二聚体变体蛋白，四价糖簇抑制的敏感性明显不同。结果教给了一个突出的教训：蛋白质设计很重要：CRD呈示的类型可能对基本适合的寡糖（例如在阵列中进行阳性测试）是否会成为原位结合伴侣具有深远影响。当形成凝集素-糖缀合物聚集体（晶格）时，其结构组织将取决于此参数。因此，进一步测试（ga）lectin变体将有助于（i）定义改变蛋白质装配的全部影响，以及（ii）解释为什么在进化过程中某些类型的设计受到青睐，除了为新型半乳凝素形式的潜在应用。其结构组织将取决于此参数。因此，进一步测试（ga）lectin变体将有助于（i）定义改变蛋白质装配的全部影响，以及（ii）解释为何在进化过程中偏爱某些类型的设计，除了为新型半乳凝素形式的潜在应用。其结构组织将取决于此参数。因此，进一步测试（ga）lectin变体将有助于（i）定义改变蛋白质装配的全部影响，以及（ii）解释为什么在进化过程中某些类型的设计受到青睐，除了为新型半乳凝素形式的潜在应用。