Identification of AL proteins from 10 λ-AL amyloidosis patients by mass spectrometry extracted from abdominal fat and heart tissue

Figures & data

Table 1. Clinical parameter and GL gene segments of the included AL amyloidosis patients and sample tissue of extractions.

GL gene segments			Case	Sample tissue	Organ involved	AAD	Sex	UMC	dFLC [mg/L]	FLC ratio	Cardiac stage1	Renal stage	Amyloid load^2
IGLV	IGLJ	IGLC
1–40	1	1	FOR138	Fat	Heart	70	m	SMM	1382	<0.1	IIIb	II	3+
1–44	3	2	FOR006	Heart	Heart	47	f	MGCS	137	<0.1	IIIa	I	–
1–44	1	1	FOR102	Fat	Heart	34	f	MM	1300	<0.1	IIIb	I	3+
1–44	2	2	FOR107	Fat	Kidney	55	m	MGCS	96	0.1	I	I	3+
1–44	3	2	FOR128	Fat	Heart	58	m	SMM	795	<0.1	IIIb	I	4+
1–44	2	2	FOR142	Fat	Kidney	50	m	SMM	117	0.1	I	I	3+
2–14	1	1	FOR101	Fat	Heart	72	m	SMM	997	<0.1	IIIb	I	4+
2–14	3	3	FOR159	Fat	Heart	77	f	SMM	187	0.1	IIIb	I	4+
3–19	2	2	FOR005	Heart	Heart	49	f	MGCS	318	<0.1	IIIb	I	–
3–19	3	2	FOR103	Fat	Heart	80	f	MGCS	430	<0.1	IIIb	I	4+

AAD: age at diagnosis, dFLC: difference between involved and uninvolved free LCs, f: female, m: male, MGCS: Monoclonal Gammopathy of Clinical Significance, MM: Multiple Myeloma, SMM: Smouldering Multiple Myeloma, UMC: underlying medical condition. 1: EURO score, 2: in fat tissue.

Figure 1. Location of mutational positions in the patient-specific LC proteins. Sequence alignment of the 10 LCs. Amino acid positions are numbered consecutively. Red: mutation, Green: non-encoded amino acid that arose from junctional diversity, Violet: uncertain position. Underlined amino acids at the C-terminus could not be resolved by cDNA sequencing and represent the amino acids of the respective GL. Above the sequence alignment, the secondary structure elements corresponding to the native structure of a LC (PDB: 6QB6-L) are shown. Arrows indicate β strands and continuous lines indicate ordered conformation. Below the sequence, number of mutations per amino acid position is plotted. Asterisks indicate a mutated position in more than 50% of all LCs. The sequences shown are composed of cDNA sequencing and MS results. Sequences corresponding to FOR005 and FOR006 were already published [28].

Figure 2. Overview of the sequence coverage of the fibril proteins of the 10 AL patients found by MS. Disulphide bonded cysteine is highlighted in yellow and pyroglutamate is highlighted in violet. The dashed lines indicate the N- and C-terminal ends.

Figure 3. Mutational effects on the biochemical and structural properties of the LC proteins. (A) Analysis of the hydrophobicity (GRAVY) and aggregation propensity (AGG). Shown are the difference values ΔGRAVY and ΔAGG between the LC proteins and their respective GL proteins separately for the V_L and C_L. (B) Analysis of the pI values. Shown are the individual pI values and the mean pI values of the LC proteins and their respective GL proteins separately for the V_L and C_L. Asterisks indicate a significant difference. (C) Location of mutations in a natively folded LC (PDB: 6QB6). Colour coding as indicated.

Annamalai K, Liberta F, Vielberg MT, et al. Common fibril structures imply systemically conserved protein misfolding pathways in vivo. Angew Chem Int Ed Engl. 2017;56(26):7510–7514.

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Data availability statement

The data that support the findings of this study are available from the corresponding author, C. H., upon reasonable request. In addition, the MS data are accessible in the MassIVE database under the dataset identifier MassIVE MSV000089772.