1.M.1 The Rz/Rz1 Spanin1 (Rz(1)) Family Bacteriophage lambda has four adjacent genes, S, R, Rz and Rz1, dedicated to host cell lysis. S encodes the holin and antiholin and R encodes the endolysin while Rz1 and Rz are an outer membrane lipoprotein (Rz1) and a type II signal anchor protein (Rz). Together they comprise a spanin. The Rz-Rz1 complex spans the periplasm ane carries out the final step in the process of host lysis. Endolysin-mediated degradation of the cell wall is a prerequisite for conformational changes in the Rz-Rz1 complex leading to the juxtaposition and fusion of the two membranes. Fusion removes the last physical barrier to efficient release of progeny virions (Berry et al. 2008; Rajaure et al. 2015). The lambda Rz and Rz1 lysis genes are remarkable in that Rz1, encoding the outer membrane lipoprotein, is completely embedded in the +1 register within Rz, which itself encodes the inner membrane protein (Summer et al. 2007; Berry et al. 2012; Berry et al. 2008; Kongari et al. 2018). 1.M.1.1 - 5 are most similar to the lambda phage i_spanin, 1.M.1.6 - 10 are derived from mycobacterial and gordonial phages and are most similar to each other, and 1.M.1.11 - 13 are derived from proteobacteria and are most similar to each other. These proteins are i-spanins. Only 1.M.1.1.1, 1.M.1.1.2 and 1.M.1.1.4 include both spanins (i-spanin and o-spanin) of the system.
This family belongs to the Spanin Superfamily.
References:
Berry, J., E.J. Summer, D.K. Struck, and R. Young. (2008). The final step in the phage infection cycle: the Rz and Rz1 lysis proteins link the inner and outer membranes. Mol. Microbiol. 70: 341-351.
Berry, J., M. Rajaure, T. Pang, and R. Young. (2012). The spanin complex is essential for lambda lysis. J. Bacteriol. 194: 5667-5674.
Khakhum, N., U. Yordpratum, A. Boonmee, U. Tattawasart, J.L. Rodrigues, and R.W. Sermswan. (2016). Identification of the Burkholderia pseudomallei bacteriophage ST79 lysis gene cassette. J Appl Microbiol. [Epub: Ahead of Print]
Kongari, R., M. Rajaure, J. Cahill, E. Rasche, E. Mijalis, J. Berry, and R. Young. (2018). Phage spanins: diversity, topological dynamics and gene convergence. BMC Bioinformatics 19: 326.
Liu, P., X. Dong, X. Cao, Q. Xie, X. Huang, J. Jiang, H. Dai, Z. Tang, Y. Lin, S. Feng, and K. Luo. (2023). Identification of Three Campylobacter Lysins and Enhancement of Their Anti-Escherichia coli Efficacy Using Colicin-Based Translocation and Receptor-Binding Domain Fusion. Microbiol Spectr 11: e0451522. [Epub: Ahead of Print]
Rajaure, M., J. Berry, R. Kongari, J. Cahill, and R. Young. (2015). Membrane fusion during phage lysis. Proc. Natl. Acad. Sci. USA 112: 5497-5502.
Summer, E.J., J. Berry, T.A. Tran, L. Niu, D.K. Struck, and R. Young. (2007). Rz/Rz1 lysis gene equivalents in phages of Gram-negative hosts. J. Mol. Biol. 373: 1098-1112.
Examples:
TC#	Name	Organismal Type	Example
1.M.1.1.1	The Spanin1 (Rz; inner membrane, IM)/Spanin2 (Rz1; outer membrane, OM) complex. Spanin1, 153 aas; Spanin2, 60 aas. Together they span the periplasm and mediate fusion of the IM and OM. By doing so, they disrupt the double membrane barrier (Berry et al. 2008; Rajaure et al. 2015; Kongari et al. 2018).		*Rz/Rz1 of E. coli* phage lambda**

1.M.1.1.10	Uncharacterized protein, SEA_CAMERICO_42, of 125 aas and 1 N-terminal TMS.		UP of Gordonia phage Camerico

1.M.1.1.11	Uncharacterized protein of 122 aas and 1 TMS.		UP of Aminobacter aminovorans

1.M.1.1.12	Uncharacterized protein of 122 aas and 1 TMS.		UP of Mesorhizobium tamadayense

1.M.1.1.13	Putative phage spanin of 126 aas and 1 N-terminal TMS.		PPS of Mesorhizobium sp.

1.M.1.1.2	*Rz/Rz1 spanin complex of Burkholderia* phage BcepIL02**	Proteobacterial virus	Rz/Rz1 of Burkholderia phage BcepIL02 Rz, (171 aas; C5IHR7) Rz1 (71 aas; C5IHR8)

1.M.1.1.3	Putative Rz (143 aas; W1IXJ3) inner membrane spanin (i-spanin) of a possible Rz/Rz1 spanin complex of lambdoid prophage Rac. No o-spanin was found, but an adjacent gene (UniProt encodes a 62 aa addiction module toxin, HicA which could be either a o-spanin or a toxin which could be exported via the Rz protein.	Proteobacteria	Rz protein of Xenorhabdus szentirmaii

1.M.1.1.4	Two component spanin consisting of Rz (IM, 145 aas and 1 TMS) and Rz1 (OM, 61 aas and 1 TMS).		*Spanin of Enterobacteria* phage P22 (Bacteriophage P22)**

1.M.1.1.5	Putative spanin of 164 aas and 1 TMS		*Putative spanin of Arsenophonus nasoniae* (son-killer infecting Nasonia vitripennis)**

1.M.1.1.6	Putative phage spanin Rz of 128 aas and 1 N-terminal TMS.		PPS of Mycobacterial phage Ptience, gene 45.

1.M.1.1.7	Putative phage spanin, Aminay, of 132 aas and 1 N-terminal TMS.		PPS of Mycobacterial phage spanin, Aminay.

1.M.1.1.8	Uncharacterized protein of 107 aas and 1 N-terminal TMS.		UP of Prescottella equi (Rhodococcus equi)

1.M.1.1.9	Uncharacterized protein, putative spanin, of 134 aas and 1 N-terminal TMS.		UP of Mycobacterium phage Rope

Examples:
TC#	Name	Organismal Type	Example
1.M.1.2.1	Rz-like/Rz1-like spanin complex; Rz-like, 148 aas and Rz1-like, 163 aas.		*Rz/Rz1 complex of Klebsiella* phage KP32**

1.M.1.2.2	Two component Spanin, eRz/eRz1 of 147 and 74 aas, respectively.		*Spanin of Pseudomonas* phage Phi15**

1.M.1.2.3	Spanin pair: i-spanin (gene 18.5; 143 aas; P03803) + o-spanin (gene 18.7; 83 aas; P03788).		Spanin pair of Phage T7

1.M.1.2.4	Uncharacterized protein of 162 aas and 1 N-terminal TMS.		*UP of Desulfovibrio* sp. (coral metagenome)**

1.M.1.2.5	Uncharacterized protein of 123 aas and 1 N-terminal TMS.		UP of E. coli phage rB

Examples:
TC#	Name	Organismal Type	Example
1.M.1.3.1	Putative two component spanin (of 109 and 89 aas, each with 1 TMS).		*Spanin of Enterobacteria* phage phiKMV (Pseudomonas phage phiKMV)**

1.M.1.3.10	Putative spanin of 248 aas and 0 TMSs		UP of Labrenzia alexandrii

1.M.1.3.11	*Two component spannin, LysB (R4JGE0)/LysC (R4JDL9) of 146 and 97 aas, respectively. LysBC can lyse E. coli* cells (Khakhum et al. 2016).**		*LysB/LysC of Burkholderia* phage ST79**

1.M.1.3.12	Uncharacterized protein of 114 aas and 1 TMS.		*UP of Acanthocystis turfacea* Chlorella virus TN603.4.2**

1.M.1.3.13	*Putative spanin (phage hypothetical protein of Tenacibaculum maritimum) of 115 aas and possibly 1 N-terminal TMS.*		Putative spanin of Tenacibaculum maritimum

1.M.1.3.14	Spanin complex consisting of inner and outer membrane spanin (i- and o-spanin) components of 162 and 129 aas, respectively.		Spannin of Caulobacter phage phiCbK

1.M.1.3.15	Spanin (inner membrane spanin of 168 aas and outer membrane spanin of 126 aas.		*Spanin of Caulobacter* phage CorColossus**

1.M.1.3.16	Putative phage spanin of 153 aas and 1 N-terminal TMS.		PPS of Histophilus somni

1.M.1.3.17	Phage spanin of 148 aas and 1 N-terminal TMS.		Spanin of Pseudoalteromonas distincta

1.M.1.3.18	*Phage spanin Rz of 145 aas and 1 N-terminal TMS, Shewanella frigidmarina* strain NCIMB 400, Gene: Sfri_1672**		*Spanin Rz of Shewanella frigidmarina* strain NCIMB 400**

1.M.1.3.19	Uncharacterized phage spanin Rz of 114 aas and 1 TMS.		Rz ofAcanthocystis turfacea Chlorella virus TN603.4.2

1.M.1.3.2	Spanin (i-spanin of 114 aas and o-spanin of 82 aas)		*Spanin of Caulobacter* phage Percy**

1.M.1.3.20	Uncharacterized protein HOR29, gp46, of 119 aas with 1 N-terminal TMS.		*UP of Pectpbacterium* phage PP2**

1.M.1.3.21	Uncharacterized protein of 119 aas		*UP of Jiella* sp. CBK1P-4**

1.M.1.3.22	Uncharacterized DUF6468 domain-containing protein of 116 aa		*UP of Aureimonas* sp. AU20**

1.M.1.3.23	Phage spanin Rz of 111 aa		Rz of Fulvimarina pelagi HTCC2506

1.M.1.3.24	*Putative phage spanin of 94 aas and 1 TMS from a Xylella* phage.**		*PPS of a Xylella* phage**

1.M.1.3.25	Putative spanin of 124 aas and 1 or 2 TMSs, where the N-terminal TMS is strongly hydrophobic while the secon putative TMS is only moderately hydrophobic.		*Putative Rz spanin of Croceibacter* phage P2559S**

1.M.1.3.26	Uncharacterized putative spanin of 107 aas and 2 TMSs, N- and C-terminal.		UP of Chryseobacterium carnipullorum

1.M.1.3.27	o-Spanin of 73 aas and 1 N-terminal TMS		*o-Spanin of Helicobacter acinonychis* strain Sheeba, prophage II, orf25.**

1.M.1.3.28	Uncharacterized protein of 84 aas and 1 TMS.		UP of Helicobacter suis

1.M.1.3.29	Uncharacterized protein of 120 aas and 1 TMS.		UP of Helicobacter suis

1.M.1.3.3	Uncharacterized putative spanin protein of 136 aas.		*Putative spanin of Burkholderia* phage Bp-AMP1**

1.M.1.3.30	Putative phage spanin of 210 aas with 1 N-terminal TMS.		Pps of Fibrella aestuarina

1.M.1.3.31	Putative phage i-spainin of 205 aas and 1 N-terminal TMS.		PPS of Spirosoma terrae

1.M.1.3.32	Uncharacterized protein of 192 aas and 1 TMS.		*UP of Spirosoma* sp. KCTC 72228**

1.M.1.3.33	Uncharacterized protein of 121 aas and 1 N-terminal TMS.		*UP of Cronobacter* phage vB_CskP**

1.M.1.3.34	*Putative lipoprotein of 79 aas with one N-terminal TMS. It may be a bacterial lysin (Liu et al.* 2023).**		*LP of Campylobacter hyointestinalis* subsp. hyointestinalis**

1.M.1.3.4	Putative inner membrane i-panin of 90 aas and 1 N-terminal TMS, Rz, and putative outer membrane spanin, o-spanin of 107 aas with 1 N-terminal TMS.		Spanin of Ralstonia phage RSJ2

1.M.1.3.5	Putative two component spanin, Rz of 118 aas and Rz1 of 83 aas.		*Rz/Rz1 of Burkholderia* phage JG068**

1.M.1.3.6	Spanin Rz/Rz1 pair of 110 and 86 aas, each with 1 N-terminal TMS		Rz/Rz1 of Caulobacter phage Cd1

1.M.1.3.7	Rz/Rz1 spanin pair of 142 and 82 aas, respectively.		Rz/Rz1 of Klebsiella pneumoniae

1.M.1.3.8	Putative spanin complex with two proteins of 109 and 136 aas, both with an N-terminal TMS.		Spanin of phage APSE-6

1.M.1.3.9	Uncharacterized spanin Rz homologue of 224 aas and 1 TMS.		*UP of Butyrivibrio* sp. AE3004**

Examples:
TC#	Name	Organismal Type	Example
1.M.1.4.10	Uncharacterized spanin of 227 aas and 0 TMSs		UP of Pseudomonas sp. StFLB209

1.M.1.4.11	Phage-like spanin of 166 aas and 1 N-terminal TMS.		PS of Albitalea terrae

1.M.1.4.12	Uncharacterized protein of 184 aas and 1 N-terminal TMS.		UP of Vibrio vulnificus

1.M.1.4.13	Rz/RzI spanin protein of 166 aas and 1 N-terminal TMS.		*Rz/RzI of Escherichia* phage IME11**

1.M.1.4.14	Uncharacterized protein, i-spanin 114 of 114 aas and 1 N-terminal TMS.		i-spanin 114 of Stutzerimonas stutzeri

1.M.1.4.15	i-spanin 114 of 114 aas and 1 N-terminal TMS.		Putative phage spanin of Stutzerimonas stutzeri

1.M.1.4.16	Uncharacterized protein of 131 aas and 1 TMS.		UP of Rhizobium leguminosarum

1.M.1.4.17	Uncharacterized protein of 108 aas and 1 N-terminal TMS.		UP of Methyloterrigena soli

1.M.1.4.18	Uncharacterized protein annotated as a P-loop NTPase superfamily protein of 131 aas and 1 TMS.		*UP of Dinoroseobacter* phage vB_DshS-R5C**

1.M.1.4.19	Uncharacterized protein of 113 aas.		UP of Myoviridae

1.M.1.4.2	Uncharacterized Rz spanin of 180 aas and 1 TMS.		Rz of Ralstonia solanacearum

1.M.1.4.20	Putative phage spanin of 138 aas and 1 N-terminal TMS.		PPS of Pseudomonas phage PAK P5 (Gene: PAK_P500031)

1.M.1.4.21	Uncharacterized protein of 123 aas and 1 N-terminal TMS.		*UP of Cronobacter* phage CR3**

1.M.1.4.22	Uncharacterized protein of 134 aas and 1 N-terminal TMS.		*UP of Cronobacter* phage vB_CsaM_GAP31**

1.M.1.4.23	Uncharacterized protein of 161 aas and 1 N-terminal TMS.		*UP of Pseudomonas* phage PhiH2**

1.M.1.4.24	*Putative spanin of Pseudomonas* phage KPP23, gene 008.**		*Putative spanin of Pseudomonas* phage KPP23**

1.M.1.4.25	Putative phage spanin of 125 aas and 1 N-terminal TMS.		PPS of Stenotrophomonas maltophilia

1.M.1.4.26	Putative phage spanin of 134 aas and 1 N-terminal TMS.		*PPS of Neisseria meningitidis* serogroup B (strain MC58)**

1.M.1.4.27	Uncharacterized protein of 217 aas and 1 N-terminal TMS.		UP of Yersinia massiliensis

1.M.1.4.28	*Uncharacterized putative phage spanin Rz of Klebsiella pneumoniae* of 211 aas and 1 N-terminal TMS.**		Putative spanin of Klebsiella pneumoniae

1.M.1.4.29	Putative phage spanin of 133 aas and 1 N-terminal TMS.		*PPS of Mesorhizobium* sp. L103C120A0**

1.M.1.4.3	Lysis system i-spanin subunit Rz of 166 aas		UP of Microvirgula aerodenitrificans

1.M.1.4.30	Putative phage spanin of 156 aas and 1 N-terminal TMS.		PPS of Oricola thermophila

1.M.1.4.31	Putative phage spanin of 120 aas and 1 N-terminal TMS.		PPS of Aeromonas phage CC2

1.M.1.4.32	Uncharacterized protein of 128 aas and 1 N-terminal TMS.		*UP of Aeromonas* phage Ah1**

1.M.1.4.33	Uncharacterized putative i-spanin protein of 98 aas.		*UP of Vibrio* phage VBM1**

1.M.1.4.34	i-Spanin of 163 aas and 1 N-terminal TMS.		*i-Spanin of Vibrio* phage SSP002**

1.M.1.4.4	Annotated as "lysozyme" of 208 aas and 1 N-terminal TMS. A member of the Pfam Phage_lysis superfamily. However, it appears to be a large spanin and is designated here as an uncharacterized protein (UP) (unpublished observations).		UP of Pseudomonas fluorescens

1.M.1.4.5	Probable spanin of 165 aas and 1 N-terminal TMS.		*Spanin of Luteibacter* sp.**

1.M.1.4.6	*Putative i-spanin of 172 aas with 1 N-terminal TMS. It is from Escherichia* phage ECML-117 (UniProt acc # I7ATQ8).**		*Spanin of Escherichia* phage ECML-117**

1.M.1.4.7	Phage spanin of 165 aas and 1 N-terminal TMS.		PS of Myoviridae sp. (insect metagenome)

1.M.1.4.8	Uncharacterized protein of 177 aas and 1 N-terminal TMS.		UP of Sphaerotilus montanus

1.M.1.4.9	*Putative phage spanin Rz of Sideroxydans lithotrophicus* (strain ES-1) of 171 aas and 1 N-terminal TMS (Uni Prot acc # D5CTS4).**		*PPS12 of Sideroxydans lithotrophicus* (strain ES-1)**

Examples:
TC#	Name	Organismal Type	Example
1.M.1.5.1	*Outer membrane lipoprotein o-spanin/inner membrane i-spanin complex, pseT.2/pseT.3 (Summer et al.* 2007).**	Bacterial virus	PseT.2/PseT.3 of enterobacterial phage T4 PseT.2 of 99 aas PseT.3 of 117 aas

1.M.1.5.2	i-spanin/o-spanin of 115/95 aas, respectively, each with an N-terminal TMS.		Spanin of Seratia phage SP1

1.M.1.5.3	i-Spanin/o-spanin of 110 aas/116 aas, respectively, both with one N-terminal TMS.		*Spanin of Enterobacter* phage ENC9**

1.M.1.5.4	Putative phage R1 spanin protein of 120 aas and 1 N-terminal TMS.		*PPS of Pectobacterium* phage Arno160**

1.M.1.5.5	Putative phage i-spanin of 149 aas and 1 N-terminal TMS (Orf046).		*PPS of Escherichia* phage vB EcoS AKFV33**