Griffith University, Institute for Glycobiology, Gold Coast, Queensland, Australia.
Department of Microbiology and Immunology and Department of Internal Medicine, The University of Iowa, Iowa City, Iowa, USA.
mBio. 2021 Mar 23;12(2):e03666-20. doi: 10.1128/mBio.03666-20.
The lipooligosaccharide (LOS) of plays key roles in pathogenesis and is composed of multiple possible glycoforms. These glycoforms are generated by the process of phase variation and by differences in the glycosyltransferase gene content of particular strains. LOS glycoforms of can be terminated with an -acetylneuraminic acid (Neu5Ac), which imparts resistance to the bactericidal activity of serum. However, cannot synthesize the CMP-Neu5Ac required for LOS biosynthesis and must acquire it from the host. In contrast, can synthesize endogenous CMP-Neu5Ac, the donor molecule for Neu5Ac, which is a component of some meningococcal capsule structures. Both species have an almost identical LOS sialyltransferase, Lst, that transfers Neu5Ac from CMP-Neu5Ac to the terminus of LOS. Lst is homologous to the LsgB sialyltransferase of nontypeable (NTHi). Studies in NTHi have demonstrated that LsgB can transfer keto-deoxyoctanoate (KDO) from CMP-KDO to the terminus of LOS in place of Neu5Ac. Here, we show that Lst can also transfer KDO to LOS in place of Neu5Ac in both and Consistent with access to the pool of CMP-KDO in the cytoplasm, we present data indicating that Lst is localized in the cytoplasm. Lst has previously been reported to be localized on the outer membrane. We also demonstrate that KDO is expressed as a terminal LOS structure in samples from infected women and further show that the anti-KDO monoclonal antibody 6E4 can mediate opsonophagocytic killing of Taken together, these studies indicate that KDO expressed on gonococcal LOS represents a new antigen for the development of vaccines against gonorrhea. The emergence of multidrug-resistant strains that are resistant to available antimicrobials is a current health emergency, and no vaccine is available to prevent gonococcal infection. Lipooligosaccharide (LOS) is one of the major virulence factors of The sialic acid -acetylneuraminic acid (Neu5Ac) is present as the terminal glycan on LOS in In this study, we made an unexpected discovery that KDO can be incorporated as the terminal glycan on LOS of by the alpha-2,3-sialyltransferase Lst. We showed that express KDO on LOS and that the KDO-specific monoclonal antibody 6E4 can direct opsonophagocytic killing of These data support further development of KDO-LOS structures as vaccine antigens for the prevention of infection by .
淋病奈瑟菌的脂寡糖（LOS）在发病机制中起着关键作用，由多种可能的糖型组成。这些糖型是通过相变异和特定菌株中糖基转移酶基因含量的差异产生的。淋病奈瑟菌 LOS 的糖型可以被终止于-N-乙酰神经氨酸（Neu5Ac），这赋予了其对血清杀菌活性的抗性。然而，淋病奈瑟菌不能合成 LOS 生物合成所需的 CMP-Neu5Ac，必须从宿主中获取。相比之下，脑膜炎奈瑟菌可以合成内源性 CMP-Neu5Ac，即神经氨酸的供体分子，它是某些脑膜炎奈瑟菌荚膜结构的组成部分。这两个物种都有一个几乎相同的 LOS 唾液酸转移酶 Lst，它将 Neu5Ac 从 CMP-Neu5Ac 转移到 LOS 的末端。Lst 与无乳链球菌（NTHi）的 LsgB 唾液酸转移酶同源。NTHi 的研究表明，LsgB 可以将 keto-deoxyoctanoate（KDO）从 CMP-KDO 转移到 LOS 的末端，取代 Neu5Ac。在这里，我们表明 Lst 也可以在 和 中，将 KDO 转移到 LOS 上，取代 Neu5Ac。与细胞质中 CMP-KDO 池的获得一致，我们提供的数据表明 Lst 定位于细胞质中。Lst 先前曾被报道定位于外膜上。我们还证明 KDO 作为末端 LOS 结构 在感染妇女的样本中表达，并进一步表明抗 KDO 单克隆抗体 6E4 可以介导对淋病奈瑟菌的调理吞噬杀伤。综上所述，这些研究表明，淋病奈瑟菌 LOS 上表达的 KDO 代表了开发淋病疫苗的一个新抗原。目前，对抗生素耐药的多重耐药淋病奈瑟菌菌株的出现是一个当前的健康紧急情况，而且没有疫苗可用于预防淋病奈瑟菌感染。脂寡糖（LOS）是淋病奈瑟菌的主要毒力因子之一。在淋病奈瑟菌中，神经氨酸-N-乙酰基（Neu5Ac）作为 LOS 的末端聚糖存在。在这项研究中，我们有一个意想不到的发现，即 KDO 可以由α-2,3-唾液酸转移酶 Lst 作为 LOS 的末端聚糖掺入淋病奈瑟菌。我们表明，淋病奈瑟菌表达 LOS 上的 KDO，并且 KDO 特异性单克隆抗体 6E4 可以指导调理吞噬杀伤。这些数据支持进一步开发 KDO-LOS 结构作为疫苗抗原，以预防感染。
