title: Branched Lateral Tail Fiber Organization in T5-Like Bacteriophages DT57C and DT571/2 is Revealed by Genetic and Functional Analysis.
abstract: The T5-like siphoviruses DT57C and DT571/2, isolated from horse feces, are very closely related to each other, and most of their structural proteins are also nearly identical to T5 phage. Their LTFs (L-shaped tail fibers), however, are composed of two proteins, LtfA and LtfB, instead of the single Ltf of bacteriophage T5. In silico and mutant analysis suggests a possible branched structure of DT57C and DT571/2 LTFs, where the LtfB protein is connected to the phage tail via the LtfA protein and with both proteins carrying receptor recognition domains. Such adhesin arrangement has not been previously recognized in siphoviruses. The LtfA proteins of our phages are found to recognize different host O-antigen types: E. coli O22-like for DT57C phage and E. coli O87 for DT571/2. LtfB proteins are identical in both phages and recognize another host receptor, most probably lipopolysaccharide (LPS) of E. coli O81 type. In these two bacteriophages, LTF function is essential to penetrate the shield of the host's O-antigens. We also demonstrate that LTF-mediated adsorption becomes superfluous when the non-specific cell protection by O-antigen is missing, allowing the phages to bind directly to their common secondary receptor, the outer membrane protein BtuB. The LTF independent adsorption was also demonstrated on an O22-like host mutant missing O-antigen O-acetylation, thus showing the biological value of this O-antigen modification for cell protection against phages.
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, build. 2, Moscow 119071, Russia. alusik81@mail.ru.
authors.forename: Alla K
authors.initials: AK
authors.lastname: Golomidova
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, build. 2, Moscow 119071, Russia. eumenius@gmail.com.|Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700, Russia. eumenius@gmail.com.
authors.forename: Eugene E
authors.initials: EE
authors.lastname: Kulikov
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, build. 2, Moscow 119071, Russia. prokhoroff@gmail.com.
authors.forename: Nikolai S
authors.initials: NS
authors.lastname: Prokhorov
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), BSP-415, 1015 Lausanne, Switzerland. ricardo.guerrero@epfl.ch.
authors.forename: Ricardo С
authors.initials: RС
authors.lastname: Guerrero-Ferreira
authors.affiliation: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, Moscow 119991, Russia. yknirel@gmail.com.
authors.forename: Yuriy A
authors.initials: YA
authors.lastname: Knirel
authors.affiliation: Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Pirogovskaya ul., 1a, Moscow 119435, Russia. el-es@yandex.ru.|Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700, Russia. el-es@yandex.ru.
authors.forename: Elena S
authors.initials: ES
authors.lastname: Kostryukova
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, build. 2, Moscow 119071, Russia. tarasyan_k@mail.ru.|A.N. Severtsov Institute of Ecology and Evolution, Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, build. 2, Moscow 119071, Russia. tarasyan_k@mail.ru.
authors.forename: Karina K
authors.initials: KK
authors.lastname: Tarasyan
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, build. 2, Moscow 119071, Russia. letarov@gmail.com.|Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700, Russia. letarov@gmail.com.
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Letarov
mesh_terms: D000595:Amino Acid Sequence; D001435:Bacteriophages / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017906:Siphoviridae / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D014764:Viral Proteins
keywords: E. coli O-antigen; O-antigen O-acetylation; T5-like phage; bacteriophage; bacteriophage adsorption; horse feces; phage branched adhesin; phage in situ evolution; tail fiber proteins