ジャーナル: RNA / 年: 2013 タイトル: Escherichia coli rimM and yjeQ null strains accumulate immature 30S subunits of similar structure and protein complement. 著者: Vivian Leong / Meredith Kent / Ahmad Jomaa / Joaquin Ortega / 要旨: Assembly of the Escherichia coli 30S ribosomal subunits proceeds through multiple parallel pathways. The protein factors RimM, YjeQ, RbfA, and Era work in conjunction to assist at the late stages of ...Assembly of the Escherichia coli 30S ribosomal subunits proceeds through multiple parallel pathways. The protein factors RimM, YjeQ, RbfA, and Era work in conjunction to assist at the late stages of the maturation process of the small subunit. However, it is unclear how the functional interplay between these factors occurs in the context of multiple parallel pathways. To understand how these factors work together, we have characterized the immature 30S subunits that accumulate in ΔrimM cells and compared them with immature 30S subunits from a ΔyjeQ strain. The cryo-EM maps obtained from these particles showed that the densities representing helices 44 and 45 in the rRNA were partially missing, suggesting mobility of these motifs. These 30S subunits were also partially depleted in all tertiary ribosomal proteins, particularly those binding in the head domain. Using image classification, we identified four subpopulations of ΔrimM immature 30S subunits differing in the amount of missing density for helices 44 and 45, as well as the amount of density existing in these maps for the underrepresented proteins. The structural defects found in these immature subunits resembled those of the 30S subunits that accumulate in the ΔyjeQ strain. These findings are consistent with an "early convergency model" in which multiple parallel assembly pathways of the 30S subunit converge into a late assembly intermediate, as opposed to the mature state. Functionally related factors will bind to this intermediate to catalyze the last steps of maturation leading to the mature 30S subunit.
ダウンロード / ファイル: emd_5598.map.gz / 形式: CCP4 / 大きさ: 7.8 MB / タイプ: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES)
注釈
Structure of the immature 30S subunit from a Escherichia coli rimM null strain. Conformation 4.
ボクセルのサイズ
X
Y
Z
EMDB情報
2
2
2
CCP4マップ ヘッダ情報
2
2
2
EM Navigator ムービー #1
2.54
2.54
2.54
密度
表面レベル
登録者による: 2.0 / ムービー #1: 2
最小 - 最大
-5.03942204 - 14.74941254
平均 (標準偏差)
0.0 (±0.98962915)
対称性
空間群: 1
詳細
EMDB XML:
マップ形状
Axis order
X
Y
Z
Origin
0
0
0
サイズ
128
128
128
Spacing
128
128
128
セル
A=B=C: 256.0 Å α=β=γ: 90.0 °
CCP4マップ ヘッダ情報:
mode
Image stored as Reals
Å/pix. X/Y/Z
2
2
2
M x/y/z
128
128
128
origin x/y/z
0.000
0.000
0.000
length x/y/z
256.000
256.000
256.000
α/β/γ
90.000
90.000
90.000
start NX/NY/NZ
-132
-122
-147
NX/NY/NZ
250
274
261
MAP C/R/S
1
2
3
start NC/NR/NS
0
0
0
NC/NR/NS
128
128
128
D min/max/mean
-5.039
14.749
0.000
-
添付データ
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試料の構成要素
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全体 : Structure of an immature 30S subunit from an E. coli rimM null st...
全体
名称: Structure of an immature 30S subunit from an E. coli rimM null strain. Conformation 4
要素
試料: Structure of an immature 30S subunit from an E. coli rimM null strain. Conformation 4
複合体: ribosome 30S subunit
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超分子 #1000: Structure of an immature 30S subunit from an E. coli rimM null st...
超分子
名称: Structure of an immature 30S subunit from an E. coli rimM null strain. Conformation 4 タイプ: sample / ID: 1000 / 集合状態: monomer / Number unique components: 1